# CalcOpenly

> 359 free online calculators for money, health, math, science, dates and units. With worked examples, formulas, charts and no sign-up.

The catalogue includes 1901 worked examples with independently sourced answers. Decimal arithmetic uses 50 significant digits; numerical methods, input precision and real-world assumptions can limit accuracy. Read each calculator's method and sources. Each page below has a Markdown version with the inputs, formula, worked examples and sources; the full set is in https://www.calcopenly.com/llms-full.txt.

## Math calculators

- [Scientific calculator](https://www.calcopenly.com/math/scientific-calculator.md): Keypad calculator with trig in degrees, radians or gradians, logs, powers, factorials, memory and a history tape — exact fractions where possible.
- [Graphing calculator](https://www.calcopenly.com/math/graphing-calculator.md): Plot several functions, polar curves and parametric curves; pan and zoom; find roots, intersections, turning points and areas.
- [Percentage calculator](https://www.calcopenly.com/math/percentage-calculator.md): Find X% of Y, what percent one number is of another, percentage increase or decrease, percent difference, and the original before a percentage was added.
- [Fraction calculator](https://www.calcopenly.com/math/fraction-calculator.md): Add, subtract, multiply and divide fractions and mixed numbers exactly, simplify to lowest terms, and convert decimals (including repeating) to fractions.
- [Ratio and proportion calculator](https://www.calcopenly.com/math/ratio-calculator.md): Simplify a ratio, solve a proportion a : b = c : x for the missing term, scale a ratio to a target, or split an amount in a given ratio, exactly.
- [Rounding and significant figures calculator](https://www.calcopenly.com/math/rounding-calculator.md): Round a number to decimal places, significant figures or the nearest ten or hundred under nine rules, including banker's rounding, floor and ceiling.
- [Exponent and root calculator](https://www.calcopenly.com/math/exponent-root-calculator.md): Raise a number to any exponent, including fractional and negative ones, or take its square, cube or nth root, with exact simplified radicals such as 5√2.
- [Logarithm calculator](https://www.calcopenly.com/math/logarithm-calculator.md): The logarithm of a number to any base, including ln and log₁₀, with change-of-base steps, or the exponent x that solves bˣ = y, exact when rational.
- [Quadratic equation solver](https://www.calcopenly.com/math/quadratic-equation-solver.md): Solve ax² + bx + c = 0 with the quadratic formula: exact roots as surds or complex numbers, the discriminant, vertex and axis of symmetry, and a graph.
- [Polynomial root finder](https://www.calcopenly.com/math/polynomial-root-finder.md): All real and complex roots of a polynomial up to degree 6, such as a cubic or quartic equation, with repeated roots found exactly and 30-digit accuracy.
- [Complex number calculator](https://www.calcopenly.com/math/complex-number-calculator.md): Add, subtract, multiply and divide complex numbers, raise them to powers, find nth roots, and convert a + bi to polar form, with an Argand diagram.
- [System of linear equations solver](https://www.calcopenly.com/math/system-of-linear-equations-solver.md): Solve 2 to 5 simultaneous linear equations exactly by Gauss–Jordan elimination, with every row operation shown, and detect no-solution or infinite cases.
- [Matrix calculator](https://www.calcopenly.com/math/matrix-calculator.md): Determinant, inverse, rank and RREF of a matrix up to 6 × 6 with every row operation shown, plus transpose, product and sum, in exact fractions.
- [Vector calculator](https://www.calcopenly.com/math/vector-calculator.md): Dot and cross products of two vectors in 2D or 3D, their magnitudes, the angle between them and the projection of one onto the other, with a drawing.
- [Prime factorization calculator](https://www.calcopenly.com/math/prime-factorization-calculator.md): Prime factorization of any whole number up to 60 digits, with a factor tree, a prime or composite verdict, its divisors and the nearest primes.
- [GCD and LCM calculator](https://www.calcopenly.com/math/gcd-lcm-calculator.md): Greatest common divisor (GCD, GCF or HCF) and least common multiple (LCM) of two or more whole numbers, with Euclid's algorithm step by step.
- [Modulo calculator](https://www.calcopenly.com/math/modulo-calculator.md): Calculate a mod n under the floored, truncated and Euclidean conventions, modular powers a^b mod m of large numbers, and modular inverses, with steps.
- [Arithmetic, geometric and Fibonacci sequence calculator](https://www.calcopenly.com/math/sequence-calculator.md): The nth term and the sum of the first n terms of an arithmetic or geometric sequence, the sum to infinity, and exact Fibonacci numbers, with a table.
- [Numerical derivative calculator](https://www.calcopenly.com/math/derivative-calculator.md): The first or second derivative of any function f(x) at a point, to about 20 significant digits by Richardson extrapolation, with the tangent line drawn.
- [Definite integral calculator](https://www.calcopenly.com/math/integral-calculator.md): The definite integral of any function f(x) between two limits, by adaptive Gauss–Kronrod quadrature to about 20 significant digits, with the area shaded.
- [Set operations calculator](https://www.calcopenly.com/math/set-operations-calculator.md): Union, intersection, differences and symmetric difference of two sets of numbers or words, with the Jaccard index and a Venn diagram.
- [Truth table generator](https://www.calcopenly.com/math/truth-table-generator.md): Truth table of a Boolean expression in up to 6 variables, with the canonical sum of products, product of sums, minterms and maxterms.
- [Roman numeral converter](https://www.calcopenly.com/math/roman-numeral-converter.md): Convert numbers to Roman numerals and Roman numerals to numbers, from 1 to 3,999 (3,999,999 with overlines), with the standard form of any numeral.
- [Long division calculator with remainders and decimals](https://www.calcopenly.com/math/long-division-calculator.md): Long division calculator that shows every step: quotient and remainder, the decimal quotient with its repeating block marked, and the fraction.
- [Mean, median and mode calculator (average calculator)](https://www.calcopenly.com/math/mean-median-mode-calculator.md): Average calculator for a list of numbers: mean, median, mode, range, count and sum, with the sorted data and the middle values highlighted.
- [Square root calculator and radical simplifier](https://www.calcopenly.com/math/square-root-calculator.md): Square root calculator: the root to up to 1,000 decimal places, simplest radical form (√72 = 6√2), a perfect-square check and cube or nth roots.
- [Scientific notation calculator and standard form converter](https://www.calcopenly.com/math/scientific-notation-calculator.md): Scientific notation calculator: convert between decimal, scientific, E and engineering notation, and add, subtract, multiply or divide with sig-fig rules.
- [Factor calculator: all factors of a number](https://www.calcopenly.com/math/factor-calculator.md): Factor calculator: every factor and factor pair of a whole number up to 10¹⁸, its prime factorization, divisor count and sum, and perfect or abundant.
- [Weighted average calculator](https://www.calcopenly.com/math/weighted-average-calculator.md): Weighted average calculator: enter values with weights, one pair per line, for the weighted mean, sum of weights and each value's contribution.

## Finance calculators

- [Currency converter](https://www.calcopenly.com/finance/currency-converter.md): Convert between 160 currencies at the latest daily reference rates, with the rate date and a 90-day history chart.
- [Loan EMI calculator](https://www.calcopenly.com/finance/emi-calculator.md): Calculate the EMI on a home, car or personal loan, the total interest, and a month-by-month amortization schedule with prepayments.
- [Mortgage calculator](https://www.calcopenly.com/finance/mortgage-calculator.md): Estimate your monthly mortgage payment with property tax, insurance, HOA and PMI, plus the amortization schedule and savings from extra payments.
- [Refinance calculator](https://www.calcopenly.com/finance/refinance-calculator.md): Compare refinancing at your planned sale or payoff month. See payments, closing costs, remaining balances and savings with cash or financed fees.
- [Loan affordability calculator](https://www.calcopenly.com/finance/loan-affordability-calculator.md): Find how much you can borrow from the monthly payment you can afford at your rate and term, and the price your down payment then buys.
- [Credit card payoff calculator](https://www.calcopenly.com/finance/credit-card-payoff-calculator.md): Calculate how long a credit card balance takes to pay off on minimum payments versus a fixed monthly payment, and the interest each costs.
- [Debt snowball vs avalanche calculator](https://www.calcopenly.com/finance/debt-snowball-avalanche-calculator.md): Compare the debt snowball (smallest balance first) and avalanche (highest rate first): months to debt-free, total interest and payoff order.
- [Car lease payment calculator](https://www.calcopenly.com/finance/lease-calculator.md): Calculate a monthly car lease payment from the price, residual value and money factor or APR, split into depreciation, finance charge and tax.
- [Compound interest calculator](https://www.calcopenly.com/finance/compound-interest-calculator.md): Calculate compound interest: the future value of a deposit plus regular contributions at any compounding frequency, including daily and continuous.
- [Simple interest calculator](https://www.calcopenly.com/finance/simple-interest-calculator.md): Calculate simple interest (I = P × r × t) and the maturity amount on a principal for a term in years, months or days.
- [SIP calculator](https://www.calcopenly.com/finance/sip-calculator.md): Calculate SIP returns: the maturity value of a monthly mutual fund SIP with an optional yearly step-up, or the SIP needed to reach a goal.
- [Time value of money calculator (future and present value)](https://www.calcopenly.com/finance/time-value-of-money-calculator.md): Solve for the future value, present value, interest rate or time of a lump sum from the other three, with any compounding, including continuous.
- [Savings goal calculator](https://www.calcopenly.com/finance/savings-goal-calculator.md): Calculate how much to save each month to reach a savings goal by a date, or how long a monthly deposit takes to get there, with interest.
- [Inflation calculator (future cost and purchasing power)](https://www.calcopenly.com/finance/inflation-calculator.md): Calculate what a purchase will cost after inflation, what your money will still buy, and your real return after inflation.
- [Salary to hourly calculator](https://www.calcopenly.com/finance/salary-to-hourly-calculator.md): Convert an annual salary to an hourly wage or hourly pay to salary, plus daily, weekly, biweekly, semimonthly and monthly pay.
- [NPV and IRR calculator (with MIRR and payback)](https://www.calcopenly.com/finance/npv-irr-calculator.md): Calculate NPV, IRR, modified IRR, payback and discounted payback for a series of periodic cash flows, with the NPV profile across rates.
- [XIRR calculator (irregular cash flows)](https://www.calcopenly.com/finance/xirr-calculator.md): Calculate XIRR, the annualized return on cash flows made on irregular dates, and XNPV at your discount rate, matching Excel's actual/365 method.
- [Bond price, yield and duration calculator](https://www.calcopenly.com/finance/bond-calculator.md): Calculate a bond's price from its yield to maturity, or the YTM from its price, with current yield, Macaulay and modified duration and convexity.
- [Black-Scholes calculator (option price and Greeks)](https://www.calcopenly.com/finance/black-scholes-option-calculator.md): Calculate European call and put prices and the Greeks (delta, gamma, theta, vega, rho) with the Black-Scholes-Merton model, including dividends.
- [Stock average cost calculator (P&L and position size)](https://www.calcopenly.com/finance/stock-position-calculator.md): Calculate your average cost per share across several buys, unrealized profit and return, and the position size for your risk and stop loss.
- [ROI and CAGR calculator](https://www.calcopenly.com/finance/roi-cagr-calculator.md): Calculate ROI (total return) and CAGR (compound annual growth rate) from an investment's start and end values, over years or between two dates.
- [Retirement calculator](https://www.calcopenly.com/finance/retirement-calculator.md): Calculate how much you need to retire on inflation-adjusted expenses, the monthly saving that gets you there, and how the money runs down.
- [Rent vs buy calculator](https://www.calcopenly.com/finance/rent-vs-buy-calculator.md): Compare renting and buying a home: net worth from owning versus renting and investing the difference, year by year, and when buying pulls ahead.
- [Break-even calculator](https://www.calcopenly.com/finance/break-even-calculator.md): Calculate the break-even point in units and sales revenue from fixed costs, price and variable cost, plus the volume needed for a target profit.
- [Depreciation calculator](https://www.calcopenly.com/finance/depreciation-calculator.md): Calculate a depreciation schedule by straight-line, declining balance, double declining, sum-of-years' digits or units of production, with book value.
- [DCF calculator (discounted cash flow valuation)](https://www.calcopenly.com/finance/dcf-valuation-calculator.md): Calculate enterprise value, equity value and value per share with a DCF: projected free cash flows plus a Gordon-growth terminal value.
- [GST, VAT and sales tax calculator](https://www.calcopenly.com/finance/gst-vat-sales-tax-calculator.md): Add GST, VAT or sales tax to a price, or remove it from a tax-inclusive price, with stacked state and local rates or India's CGST/SGST split.
- [Income tax calculator](https://www.calcopenly.com/finance/income-tax-calculator.md): Calculate income tax for India FY 2025-26 (new vs old regime), US federal 2025 and UK 2025-26, with take-home pay and marginal and effective rates.
- [Auto loan calculator](https://www.calcopenly.com/finance/auto-loan-calculator.md): Auto loan calculator: monthly car payment with trade-in, amount owed, sales tax and fees, total interest, a payment schedule, or the price a budget buys.
- [Mortgage payoff calculator](https://www.calcopenly.com/finance/mortgage-payoff-calculator.md): Mortgage payoff calculator: new payoff date, months and interest saved by extra monthly, yearly or one-time payments, or the extra to finish by a date.
- [Amortization schedule calculator](https://www.calcopenly.com/finance/amortization-schedule-calculator.md): Amortization calculator: payment, dated schedule and yearly totals for monthly, biweekly or weekly payments, with principal and interest in each.
- [Student loan calculator](https://www.calcopenly.com/finance/student-loan-calculator.md): Student loan calculator: payment, total interest and payoff date on the federal standard, tiered or extended plan or a custom term, with extra payments.
- [Debt consolidation calculator](https://www.calcopenly.com/finance/debt-consolidation-calculator.md): Debt consolidation calculator: compare your debts with one loan — monthly payment, total interest, payoff time, APR with fees and the break-even rate.
- [FHA loan calculator](https://www.calcopenly.com/finance/fha-loan-calculator.md): FHA loan payment with the 1.75% upfront MIP, the annual MIP from HUD's current table, taxes and insurance, and a check against your county's 2026 loan limit.
- [VA loan calculator](https://www.calcopenly.com/finance/va-loan-calculator.md): VA loan payment with the VA funding fee from the current table (first or later use, by down payment), the financed loan amount, taxes and insurance.
- [HELOC and home equity calculator](https://www.calcopenly.com/finance/home-equity-loan-calculator.md): Home equity you can borrow at your lender's CLTV limit, and HELOC payments in the interest-only draw period and the repayment period, or a fixed home equity loan.
- [Canadian mortgage calculator](https://www.calcopenly.com/finance/canadian-mortgage-calculator.md): Canadian mortgage payment with semi-annual compounding, accelerated bi-weekly or weekly options, the CMHC insurance premium and the balance at renewal.
- [Down payment calculator](https://www.calcopenly.com/finance/down-payment-calculator.md): Down payment and closing costs you need, how long your savings take to reach them (or the monthly saving needed), and the PMI cost below 20% down.
- [401k calculator](https://www.calcopenly.com/finance/401k-calculator.md): Calculate your 401(k) balance at retirement from salary, contribution rate and a two-tier employer match, with 2026 IRS limits and catch-up.
- [Roth IRA calculator](https://www.calcopenly.com/finance/roth-ira-calculator.md): Calculate your 2026 Roth IRA contribution limit after the income phase-out, its growth, and whether a Roth or traditional IRA leaves more after tax.
- [CD calculator](https://www.calcopenly.com/finance/cd-calculator.md): Calculate CD interest and maturity value from the APY or APR and compounding, convert APY to APR, and see what an early withdrawal penalty costs.
- [Annuity calculator (growth and payout)](https://www.calcopenly.com/finance/annuity-calculator.md): Calculate an annuity's future value from regular payments, the payout a lump sum buys over N years, or how long it lasts at a set withdrawal.
- [RMD calculator (required minimum distribution)](https://www.calcopenly.com/finance/rmd-calculator.md): Calculate your required minimum distribution from the IRS Uniform Lifetime or joint table, your RMD starting age (73 or 75), and future RMDs.
- [APR calculator](https://www.calcopenly.com/finance/apr-calculator.md): Calculate a loan's APR with fees by the Regulation Z actuarial method, the amount financed, the finance charge and the effective annual rate.
- [Paycheck calculator](https://www.calcopenly.com/finance/paycheck-calculator.md): Calculate US take-home pay per paycheck and per year: 2026 federal withholding (IRS Pub. 15-T), Social Security, Medicare, state tax and deductions.
- [House affordability calculator](https://www.calcopenly.com/finance/house-affordability-calculator.md): Find how much house you can afford: the highest home price whose payment, tax, insurance, HOA and PMI fit the 28% and 36% debt-to-income limits.
- [Debt-to-income ratio calculator (DTI)](https://www.calcopenly.com/finance/debt-to-income-ratio-calculator.md): Calculate your debt-to-income ratio (DTI), front-end and back-end, against lender limits, and the debt cut or income rise that reaches your target.
- [Commission calculator](https://www.calcopenly.com/finance/commission-calculator.md): Calculate sales commission at a flat or tiered rate, total pay with base salary, the effective rate, and the sales needed to earn a target commission.
- [Rental property calculator (cap rate and cash flow)](https://www.calcopenly.com/finance/rental-property-calculator.md): Calculate a rental property's cap rate, NOI, monthly cash flow, cash-on-cash return and IRR, with a year-by-year projection of rent, value and equity.

## Geometry calculators

- [Area and perimeter calculator for 2D shapes](https://www.calcopenly.com/geometry/shape-area-perimeter-calculator.md): Area and perimeter of 15 plane shapes, from rectangles, triangles and trapezoids to circles, ellipses, regular polygons and rings, drawn to scale.
- [Volume and surface area calculator for 3D shapes](https://www.calcopenly.com/geometry/volume-surface-area-calculator.md): Volume, surface area, slant height and capacity in litres for 14 solids, including cylinders, cones, spheres, pyramids, prisms, tori and ellipsoids.
- [Triangle calculator: solve SSS, SAS, ASA, AAS and SSA](https://www.calcopenly.com/geometry/triangle-solver.md): Missing sides, angles, area, perimeter, heights, inradius and circumradius of any triangle from three measurements, with both SSA answers.
- [Right triangle calculator: hypotenuse, sides and angles](https://www.calcopenly.com/geometry/right-triangle-calculator.md): Hypotenuse, missing leg, both acute angles, area and perimeter of a right triangle from any two values, using Pythagoras' theorem and SOHCAHTOA.
- [Circle calculator: area, circumference and radius](https://www.calcopenly.com/geometry/circle-calculator.md): Area, circumference, radius and diameter of a circle from any one of them, plus arc length, chord, sector and segment area for a central angle.
- [Trig calculator: sin, cos, tan and their inverses](https://www.calcopenly.com/geometry/trig-functions-calculator.md): sin, cos, tan, sec, csc and cot of an angle in degrees, radians or gradians, exact at multiples of 15°, plus inverse functions with all solutions.
- [Slope, distance and midpoint calculator: line through two points](https://www.calcopenly.com/geometry/coordinate-geometry-calculator.md): Distance, midpoint and slope between two points, the line's equation in slope-intercept, standard and point-slope form, and where two lines meet.
- [Circle through three points: centre, radius and equation](https://www.calcopenly.com/geometry/circle-through-three-points.md): Centre, radius and equation of the circle through three points, in standard form (x − h)² + (y − k)² = r² and general form, plus area.
- [Angle converter: degrees, radians, DMS and gradians](https://www.calcopenly.com/geometry/angle-dms-converter.md): Convert angles between decimal degrees, degrees-minutes-seconds (DMS), radians, gradians, turns, arcminutes, arcseconds and milliradians.
- [Roof pitch and slope calculator: angle, grade and rise over run](https://www.calcopenly.com/geometry/slope-roof-pitch-calculator.md): Angle, percent grade and roof pitch (x in 12) from rise and run or from any one of them, with the sloped length and rafter factor.
- [Polygon angle calculator: interior and exterior angles](https://www.calcopenly.com/geometry/polygon-angles-calculator.md): Sum of interior angles, each interior and exterior angle of a regular polygon and the number of diagonals, from the number of sides or one angle.
- [Polygon area from coordinates: shoelace formula calculator](https://www.calcopenly.com/geometry/polygon-area-from-coordinates.md): Area, perimeter and centroid of any simple polygon from its vertex coordinates, using the shoelace (surveyor's) formula with every term shown.

## Health and fitness calculators

- [BMI calculator](https://www.calcopenly.com/health/bmi-calculator.md): Body mass index (BMI) from height and weight in metric or imperial units, with the WHO adult category and the healthy weight range for your height.
- [Body fat calculator](https://www.calcopenly.com/health/body-fat-calculator.md): Body fat percentage by the US Navy tape method, Jackson-Pollock 3- or 7-site skinfolds, or from BMI, with fat and lean mass and the ACE category.
- [Ideal weight calculator](https://www.calcopenly.com/health/ideal-weight-calculator.md): Ideal body weight (IBW) for your height and sex by the Devine, Robinson, Miller and Hamwi formulas, with the healthy BMI weight range.
- [Waist-to-hip and waist-to-height ratio calculator](https://www.calcopenly.com/health/waist-to-hip-ratio-calculator.md): Waist-to-hip ratio and waist-to-height ratio from tape measurements, with the WHO risk cut-offs, the NICE bands and the WHO waist size category.
- [Lean body mass calculator](https://www.calcopenly.com/health/lean-body-mass-calculator.md): Lean body mass (LBM) from height, weight and sex by the Boer, James and Hume formulas, with the implied body fat percentage.
- [Body surface area calculator](https://www.calcopenly.com/health/body-surface-area-calculator.md): Body surface area (BSA) in m² from height and weight by the Mosteller, DuBois and Haycock formulas, with the spread between them.
- [BMR and TDEE calculator](https://www.calcopenly.com/health/bmr-tdee-calculator.md): Basal metabolic rate (BMR) by Mifflin-St Jeor, Harris-Benedict or Katch-McArdle, and daily calorie needs (TDEE) for five activity levels.
- [Calorie and macro calculator](https://www.calcopenly.com/health/calorie-macro-calculator.md): Daily calorie target for losing, maintaining or gaining weight, with macros in grams of protein, carbohydrate and fat per day and per meal.
- [Protein intake calculator](https://www.calcopenly.com/health/protein-intake-calculator.md): Daily protein intake in grams from body weight, goal and training level, using published g/kg ranges, with a per-meal split.
- [Water intake calculator](https://www.calcopenly.com/health/water-intake-calculator.md): Daily water intake in litres, glasses and fl oz from body weight, exercise and climate, compared with EFSA and US adequate intakes.
- [Heart rate zone calculator](https://www.calcopenly.com/health/heart-rate-zone-calculator.md): Heart rate zones from your maximum heart rate (220 − age, Tanaka, Gulati for women, or measured) by the Karvonen or percent-of-max method, with a target heart rate.
- [VO2 max calculator](https://www.calcopenly.com/health/vo2-max-calculator.md): VO2 max from the Cooper 12-minute run, the Rockport 1-mile walk or the resting heart-rate ratio, rated against Cooper Institute norms for age and sex.
- [One-rep max calculator](https://www.calcopenly.com/health/one-rep-max-calculator.md): One-rep max (1RM) from a set of reps with the Epley, Brzycki, Lombardi and O'Conner equations, plus training loads from 50 % to 100 %.
- [Running pace calculator](https://www.calcopenly.com/health/running-pace-calculator.md): Running pace per km or mile from distance and time, or finish time or distance from pace, with even splits and Riegel race predictions.
- [Cycling and swimming pace calculator](https://www.calcopenly.com/health/cycling-swimming-pace-calculator.md): Cycling power-to-weight (W/kg), speed and pace, or swimming pace per 100 m and 100 yd with your SWOLF score.
- [Calories burned calculator](https://www.calcopenly.com/health/calories-burned-calculator.md): Calories burned by an activity from its MET value in the Compendium of Physical Activities, your body weight and the time spent.
- [Steps to distance and calories calculator](https://www.calcopenly.com/health/steps-to-distance-calculator.md): Steps to distance in km and miles from a step length based on your height or measured, with walking time and calories from the ACSM equation.
- [Pregnancy due date calculator](https://www.calcopenly.com/health/pregnancy-due-date-calculator.md): Pregnancy due date from the last period, conception date or IVF transfer, with today's gestational age, trimester and milestones (ACOG).
- [Ovulation and fertile window calculator](https://www.calcopenly.com/health/ovulation-calculator.md): Ovulation date, fertile window and next period for the coming cycles, from the first day of your last period and your cycle length.
- [Blood pressure category calculator](https://www.calcopenly.com/health/blood-pressure-category-calculator.md): Blood pressure category (AHA/ACC) for a systolic/diastolic reading, from normal to stage 2 and severe hypertension, with pulse pressure and MAP.
- [Blood sugar converter (mg/dL to mmol/L)](https://www.calcopenly.com/health/blood-sugar-converter.md): Glucose from mg/dL to mmol/L and back, and HbA1c to estimated average glucose (eAG) and IFCC mmol/mol, with ADA categories.
- [Dosage by weight calculator](https://www.calcopenly.com/health/dosage-by-weight-calculator.md): Dose by weight from a mg/kg rate and body weight, capped at the single and daily maximum, with the liquid volume in mL for a given strength.
- [Blood alcohol content (BAC) calculator](https://www.calcopenly.com/health/blood-alcohol-calculator.md): Blood alcohol content (BAC) estimate by the Widmark formula from drinks, body weight and time, with the elimination curve and time back to zero.
- [Sleep cycle calculator](https://www.calcopenly.com/health/sleep-cycle-calculator.md): Bedtimes for a wake-up time, or wake-up times for a bedtime, counted in 90-minute sleep cycles plus the time it takes to fall asleep.
- [Caffeine half-life calculator](https://www.calcopenly.com/health/caffeine-half-life-calculator.md): How much caffeine is left in your body from up to three doses, based on its half-life, and when the level drops below an amount you choose.
- [Pregnancy weight gain calculator](https://www.calcopenly.com/health/pregnancy-weight-gain-calculator.md): Recommended pregnancy weight gain by pre-pregnancy BMI (IOM 2009), for singletons or twins, with the weekly rate and a week-by-week chart of your gain.
- [Conception calculator: when did I conceive?](https://www.calcopenly.com/health/conception-calculator.md): Estimated conception date and fertile window from a due date, the last period or an ultrasound, with the likely range for each dating method.
- [Period calculator: next period dates](https://www.calcopenly.com/health/period-calculator.md): Next period date and the following 5 predicted periods, with each cycle's fertile window and ovulation day, from your last period and average cycle length.
- [Army body fat calculator (2026 waist-to-height standard)](https://www.calcopenly.com/health/army-body-fat-calculator.md): Army body fat standard for 2026: your waist-to-height ratio, pass or fail against 0.55 (AD 2026-13), the largest passing waist for your height and margin.
- [GFR calculator (eGFR, CKD-EPI 2021)](https://www.calcopenly.com/health/gfr-calculator.md): eGFR from serum creatinine (mg/dL or µmol/L), age and sex by the race-free CKD-EPI 2021 equation, with optional cystatin C and the KDIGO G1–G5 stage.

## Date and time calculators

- [Days between dates calculator](https://www.calcopenly.com/datetime/date-difference-calculator.md): Days between two dates, also as years, months and days, weeks and hours, plus business days after weekends and your own holidays.
- [Age calculator](https://www.calcopenly.com/datetime/age-calculator.md): Exact age from a date of birth in years, months and days on any date, with the next birthday and age in months, weeks, days and hours.
- [Add or subtract days from a date](https://www.calcopenly.com/datetime/add-subtract-days.md): The date a number of days, weeks, months, years or business days after or before a start date, with its weekday and the calendar days moved.
- [Countdown calculator: time until a date](https://www.calcopenly.com/datetime/countdown-calculator.md): Countdown to a date: days, hours, minutes and seconds until (or since) a date and time in any time zone, ticking live and allowing for clock changes.
- [Time zone converter and meeting planner](https://www.calcopenly.com/datetime/time-zone-converter.md): Time zone converter: turn a time in one zone into local time in up to 12 others, with daylight-saving changes applied and a meeting planner grid.
- [Time calculator: add and subtract hours and minutes](https://www.calcopenly.com/datetime/time-duration-calculator.md): Add and subtract hours, minutes and seconds from a list of durations, with the total as H:MM:SS, decimal hours, minutes and seconds.
- [Hours calculator: hours between two times and weekly timesheet](https://www.calcopenly.com/datetime/hours-calculator.md): Calculate work hours, breaks and weekly timesheets. Use dates and a time zone for overnight shifts across daylight-saving changes and repeated hours.
- [Business days calculator: add working days to a date](https://www.calcopenly.com/datetime/working-days-deadline-calculator.md): The deadline N business days after or before a start date, skipping weekends and the holidays you list, with the calendar days it spans.
- [Unix timestamp converter](https://www.calcopenly.com/datetime/unix-timestamp-converter.md): Unix timestamp converter: epoch seconds, milliseconds, microseconds or nanoseconds to an ISO 8601 UTC date and local time, and dates back to epoch time.
- [Week number and day of year](https://www.calcopenly.com/datetime/week-number-day-of-year.md): Week number for any date: ISO 8601 week and week-numbering year, US week number, day of the year, days left in the year and the quarter.
- [Day of the week calculator](https://www.calcopenly.com/datetime/day-of-the-week-calculator.md): Day of the week for any date, past or future: the weekday in the Gregorian calendar, worked through step by step with Zeller's congruence.
- [Calendar converter (Hijri, Hebrew, Persian, Julian)](https://www.calcopenly.com/datetime/calendar-converter.md): Convert a Gregorian date to Hijri (Umm al-Qura and tabular), Hebrew, Persian, Indian national (Saka) and Julian dates, or a Julian date back.
- [Leap year checker](https://www.calcopenly.com/datetime/leap-year-checker.md): Leap year checker: whether a year has 366 days under the Gregorian rule, which test decides it, and the previous and next leap years.
- [Sunrise and sunset calculator](https://www.calcopenly.com/datetime/sunrise-sunset-calculator.md): Sunrise and sunset times for any place and date, with solar noon, day length and civil twilight, worked out with NOAA's solar calculator method.
- [Military time converter (24-hour time)](https://www.calcopenly.com/datetime/military-time-converter.md): Military time converter: 12-hour to 24-hour time and back, how it is spoken, time-zone letters with the Zulu equivalent, and a full-day chart.

## Unit converters

- [Length converter](https://www.calcopenly.com/conversion/length-converter.md): Convert miles to km, feet to metres, inches to cm and 16 other length units with exact factors. Accepts feet and inches such as 5 ft 11 in.
- [Area converter](https://www.calcopenly.com/conversion/area-converter.md): Convert square feet to square metres, acres to hectares and sq ft to Indian land units (guntha, cent, bigha, marla, kanal, ground), with exact factors.
- [Volume converter](https://www.calcopenly.com/conversion/volume-converter.md): Convert gallons to litres, cups to mL and fl oz to mL exactly, with US and imperial gallons, pints and fluid ounces kept separate.
- [Weight converter (kg, lb, stone, oz)](https://www.calcopenly.com/conversion/weight-converter.md): Convert kg to lbs, pounds to kg, stone to kg and ounces to grams with the exact 1959 pound, plus tonnes, carats, troy ounces and tola.
- [Temperature converter](https://www.calcopenly.com/conversion/temperature-converter.md): Convert Celsius to Fahrenheit, °F to °C and both to kelvin with °F = °C × 9/5 + 32. Includes Rankine and Réaumur; rejects values below absolute zero.
- [Time converter](https://www.calcopenly.com/conversion/time-converter.md): Convert minutes to hours, hours to days, weeks to days and years to seconds, from nanoseconds to millennia, with the 365.2425-day Gregorian year.
- [Speed converter](https://www.calcopenly.com/conversion/speed-converter.md): Convert mph to km/h, km/h to mph, m/s and knots with exact factors, plus ft/s, Mach at sea level and the speed of light.
- [Pressure converter](https://www.calcopenly.com/conversion/pressure-converter.md): Convert psi to bar, bar to psi, kPa, atm, hPa, mmHg and inHg for tyre, weather and blood pressure readings, with the exact factor chain.
- [Energy converter](https://www.calcopenly.com/conversion/energy-converter.md): Convert kWh to BTU, calories to joules, kcal to kJ and therms to kWh, using the exact definitions of the joule, calorie, BTU and electronvolt.
- [Power converter](https://www.calcopenly.com/conversion/power-converter.md): Convert hp to kW, kW to hp, watts to horsepower and BTU/h to tons of refrigeration, with mechanical (745.7 W) and metric (735.5 W) horsepower.
- [Force converter](https://www.calcopenly.com/conversion/force-converter.md): Convert kgf to newtons, lbf to N and kN to kgf or lbf, using standard gravity (9.80665 m/s²) and the exact pound-force of 4.4482216152605 N.
- [Torque converter (N·m, lb-ft)](https://www.calcopenly.com/conversion/torque-converter.md): Convert N·m to lb-ft, lb-ft to N·m, lb-in and kgf·m for torque wrench and bolt specifications, using 1 lbf·ft = 1.3558179483314004 N·m exactly.
- [Data storage converter](https://www.calcopenly.com/conversion/data-storage-converter.md): Convert GB to MB, TB to GB and GiB to GB with decimal (kB, MB, GB, TB) and binary (KiB, MiB, GiB, TiB) prefixes kept apart, plus bits and bytes.
- [Data transfer rate converter (Mbps to MB/s)](https://www.calcopenly.com/conversion/data-transfer-rate-converter.md): Convert Mbps to MB/s, Gbps to MB/s and kbps to kB/s. Network speeds are quoted in bits per second; file sizes and download meters in bytes.
- [Angle converter](https://www.calcopenly.com/conversion/angle-converter.md): Convert degrees to radians and radians to degrees, plus gradians, arcminutes, arcseconds, turns and milliradians, with π carried to 50 digits.
- [Fuel economy converter (mpg to L/100 km)](https://www.calcopenly.com/conversion/fuel-economy-converter.md): Convert mpg to L/100 km, L/100 km to mpg and km/L for US and UK gallons, using L/100 km = 235.215 ÷ US mpg or 282.481 ÷ UK mpg.
- [Frequency converter](https://www.calcopenly.com/conversion/frequency-converter.md): Convert rpm to Hz, Hz to rpm, BPM to Hz, GHz to MHz and hertz to radians per second (ω = 2πf), from Hz to THz.
- [Density converter](https://www.calcopenly.com/conversion/density-converter.md): Convert g/cm³ to kg/m³, kg/m³ to lb/ft³ and lb/gal (ppg), and g/mL to kg/L, with exact factors from the 1959 pound and foot.
- [Flow rate converter](https://www.calcopenly.com/conversion/flow-rate-converter.md): Convert L/min to gpm, gpm to L/min, cfm to m³/h and m³/h to L/s for pumps, plumbing and ventilation, with the exact US gallon and cubic foot.
- [Acceleration converter](https://www.calcopenly.com/conversion/acceleration-converter.md): Convert g-force to m/s², m/s² to g, ft/s² and gal (cm/s²), using standard gravity g₀ = 9.80665 m/s² exactly.
- [Cups to grams converter for cooking and baking](https://www.calcopenly.com/conversion/cooking-converter.md): Convert cups to grams, and grams to cups, for 27 baking ingredients including flour, sugar and butter, using King Arthur Baking and USDA weight charts.
- [Shoe size converter](https://www.calcopenly.com/conversion/shoe-size-converter.md): Convert shoe sizes between US men's and women's, UK, EU, India, Japan and Mondopoint via foot length, using the ISO/TS 19407 formulas.
- [Clothing size converter for US, UK and EU sizes](https://www.calcopenly.com/conversion/clothing-size-converter.md): Convert clothing sizes between US, UK, EU, German, Italian and Japanese labels for women's dresses and tops, men's suits and shirt collars.
- [CSS unit converter (px to rem, em, pt)](https://www.calcopenly.com/conversion/css-unit-converter.md): Convert px to rem, em, pt, picas, inches and mm using your root font size, parent font size and DPI. CSS fixes 1 in = 96 px = 72 pt.
- [Lakh, crore, million and billion converter (number to words)](https://www.calcopenly.com/conversion/lakh-crore-million-billion-converter.md): Convert lakh and crore to million and billion, and write any number in words in the Indian and international systems, or turn words back into digits.
- [SI and metric prefix converter](https://www.calcopenly.com/conversion/si-prefix-converter.md): Convert between SI metric prefixes such as giga, mega, kilo, milli, micro and nano, from quecto (10⁻³⁰) to quetta (10³⁰), including the 2022 additions.
- [Download time calculator](https://www.calcopenly.com/conversion/download-time-calculator.md): Calculate how long a file takes to download or upload from its size in MB, GB or TB and your internet speed in Mbps, allowing for protocol overhead.
- [Height and weight converter: cm to feet and inches, kg to stone](https://www.calcopenly.com/conversion/height-weight-converter.md): Convert height from cm to feet and inches and back, and weight from kg to pounds or stones and pounds, using the exact 2.54 cm inch.
- [Centimeters to inches converter](https://www.calcopenly.com/conversion/cm-to-inches.md): Convert centimeters to inches (cm to inches) with the exact factor, a conversion chart and worked steps.
- [Inches to centimeters converter](https://www.calcopenly.com/conversion/inches-to-cm.md): Convert inches to centimeters (inches to cm) with the exact factor, a conversion chart and worked steps.
- [Millimeters to inches converter](https://www.calcopenly.com/conversion/mm-to-inches.md): Convert millimeters to inches (mm to inches) with the exact factor, a conversion chart and worked steps.
- [Inches to millimeters converter](https://www.calcopenly.com/conversion/inches-to-mm.md): Convert inches to millimeters (inches to mm) with the exact factor, a conversion chart and worked steps.
- [Meters to feet converter](https://www.calcopenly.com/conversion/meters-to-feet.md): Convert meters to feet (meters to feet) with the exact factor, a conversion chart and worked steps.
- [Feet to meters converter](https://www.calcopenly.com/conversion/feet-to-meters.md): Convert feet to meters (feet to meters) with the exact factor, a conversion chart and worked steps.
- [Kilometers to miles converter](https://www.calcopenly.com/conversion/km-to-miles.md): Convert kilometers to miles (km to miles) with the exact factor, a conversion chart and worked steps.
- [Miles to kilometers converter](https://www.calcopenly.com/conversion/miles-to-km.md): Convert miles to kilometers (miles to km) with the exact factor, a conversion chart and worked steps.
- [Feet to inches converter](https://www.calcopenly.com/conversion/feet-to-inches.md): Convert feet to inches (feet to inches) with the exact factor, a conversion chart and worked steps.
- [Inches to feet converter](https://www.calcopenly.com/conversion/inches-to-feet.md): Convert inches to feet (inches to feet) with the exact factor, a conversion chart and worked steps.
- [Centimeters to feet converter](https://www.calcopenly.com/conversion/cm-to-feet.md): Convert centimeters to feet (cm to feet) with the exact factor, a conversion chart and worked steps.
- [Feet to centimeters converter](https://www.calcopenly.com/conversion/feet-to-cm.md): Convert feet to centimeters (feet to cm) with the exact factor, a conversion chart and worked steps.
- [Yards to meters converter](https://www.calcopenly.com/conversion/yards-to-meters.md): Convert yards to meters (yards to meters) with the exact factor, a conversion chart and worked steps.
- [Meters to yards converter](https://www.calcopenly.com/conversion/meters-to-yards.md): Convert meters to yards (meters to yards) with the exact factor, a conversion chart and worked steps.
- [Meters to inches converter](https://www.calcopenly.com/conversion/meters-to-inches.md): Convert meters to inches (meters to inches) with the exact factor, a conversion chart and worked steps.
- [Kilograms to pounds converter](https://www.calcopenly.com/conversion/kg-to-lbs.md): Convert kilograms to pounds (kg to lbs) with the exact factor, a conversion chart and worked steps.
- [Pounds to kilograms converter](https://www.calcopenly.com/conversion/lbs-to-kg.md): Convert pounds to kilograms (lbs to kg) with the exact factor, a conversion chart and worked steps.
- [Grams to ounces converter](https://www.calcopenly.com/conversion/grams-to-ounces.md): Convert grams to ounces (grams to ounces) with the exact factor, a conversion chart and worked steps.
- [Ounces to grams converter](https://www.calcopenly.com/conversion/ounces-to-grams.md): Convert ounces to grams (ounces to grams) with the exact factor, a conversion chart and worked steps.
- [Stone to kilograms converter](https://www.calcopenly.com/conversion/stones-to-kg.md): Convert stone to kilograms (stone to kg) with the exact factor, a conversion chart and worked steps.
- [Kilograms to stone converter](https://www.calcopenly.com/conversion/kg-to-stones.md): Convert kilograms to stone (kg to stone) with the exact factor, a conversion chart and worked steps.
- [Stone to pounds converter](https://www.calcopenly.com/conversion/stones-to-lbs.md): Convert stone to pounds (stone to lbs) with the exact factor, a conversion chart and worked steps.
- [Grams to pounds converter](https://www.calcopenly.com/conversion/grams-to-pounds.md): Convert grams to pounds (grams to pounds) with the exact factor, a conversion chart and worked steps.
- [Milliliters to US fluid ounces converter](https://www.calcopenly.com/conversion/ml-to-oz.md): Convert milliliters to US fluid ounces (ml to oz) with the exact factor, a conversion chart and worked steps.
- [US fluid ounces to milliliters converter](https://www.calcopenly.com/conversion/oz-to-ml.md): Convert US fluid ounces to milliliters (oz to ml) with the exact factor, a conversion chart and worked steps.
- [Liters to US gallons converter](https://www.calcopenly.com/conversion/liters-to-gallons.md): Convert liters to US gallons (liters to gallons) with the exact factor, a conversion chart and worked steps.
- [US gallons to liters converter](https://www.calcopenly.com/conversion/gallons-to-liters.md): Convert US gallons to liters (gallons to liters) with the exact factor, a conversion chart and worked steps.
- [US cups to milliliters converter](https://www.calcopenly.com/conversion/cups-to-ml.md): Convert US cups to milliliters (cups to ml) with the exact factor, a conversion chart and worked steps.
- [Milliliters to US cups converter](https://www.calcopenly.com/conversion/ml-to-cups.md): Convert milliliters to US cups (ml to cups) with the exact factor, a conversion chart and worked steps.
- [US tablespoons to milliliters converter](https://www.calcopenly.com/conversion/tablespoons-to-ml.md): Convert US tablespoons to milliliters (tablespoons to ml) with the exact factor, a conversion chart and worked steps.
- [US teaspoons to milliliters converter](https://www.calcopenly.com/conversion/teaspoons-to-ml.md): Convert US teaspoons to milliliters (teaspoons to ml) with the exact factor, a conversion chart and worked steps.
- [US cups to US fluid ounces converter](https://www.calcopenly.com/conversion/cups-to-ounces.md): Convert US cups to US fluid ounces (cups to oz) with the exact factor, a conversion chart and worked steps.
- [US quarts to liters converter](https://www.calcopenly.com/conversion/quarts-to-liters.md): Convert US quarts to liters (quarts to liters) with the exact factor, a conversion chart and worked steps.
- [Square feet to square meters converter](https://www.calcopenly.com/conversion/square-feet-to-square-meters.md): Convert square feet to square meters (sq ft to sq m) with the exact factor, a conversion chart and worked steps.
- [Square meters to square feet converter](https://www.calcopenly.com/conversion/square-meters-to-square-feet.md): Convert square meters to square feet (sq m to sq ft) with the exact factor, a conversion chart and worked steps.
- [Acres to square feet converter](https://www.calcopenly.com/conversion/acres-to-square-feet.md): Convert acres to square feet (acres to sq ft) with the exact factor, a conversion chart and worked steps.
- [Square feet to acres converter](https://www.calcopenly.com/conversion/square-feet-to-acres.md): Convert square feet to acres (sq ft to acres) with the exact factor, a conversion chart and worked steps.
- [Acres to hectares converter](https://www.calcopenly.com/conversion/acres-to-hectares.md): Convert acres to hectares (acres to hectares) with the exact factor, a conversion chart and worked steps.
- [Hectares to acres converter](https://www.calcopenly.com/conversion/hectares-to-acres.md): Convert hectares to acres (hectares to acres) with the exact factor, a conversion chart and worked steps.
- [Miles per hour to kilometers per hour converter](https://www.calcopenly.com/conversion/mph-to-kmh.md): Convert miles per hour to kilometers per hour (mph to km/h) with the exact factor, a conversion chart and worked steps.
- [Kilometers per hour to miles per hour converter](https://www.calcopenly.com/conversion/kmh-to-mph.md): Convert kilometers per hour to miles per hour (km/h to mph) with the exact factor, a conversion chart and worked steps.
- [Knots to miles per hour converter](https://www.calcopenly.com/conversion/knots-to-mph.md): Convert knots to miles per hour (knots to mph) with the exact factor, a conversion chart and worked steps.
- [Psi to bar converter](https://www.calcopenly.com/conversion/psi-to-bar.md): Convert psi to bar (psi to bar) with the exact factor, a conversion chart and worked steps.
- [Bar to psi converter](https://www.calcopenly.com/conversion/bar-to-psi.md): Convert bar to psi (bar to psi) with the exact factor, a conversion chart and worked steps.
- [Psi to kilopascals converter](https://www.calcopenly.com/conversion/psi-to-kpa.md): Convert psi to kilopascals (psi to kPa) with the exact factor, a conversion chart and worked steps.
- [Kilopascals to psi converter](https://www.calcopenly.com/conversion/kpa-to-psi.md): Convert kilopascals to psi (kPa to psi) with the exact factor, a conversion chart and worked steps.
- [Kilocalories to kilojoules converter](https://www.calcopenly.com/conversion/kcal-to-kj.md): Convert kilocalories to kilojoules (kcal to kJ) with the exact factor, a conversion chart and worked steps.
- [Kilojoules to kilocalories converter](https://www.calcopenly.com/conversion/kj-to-kcal.md): Convert kilojoules to kilocalories (kJ to kcal) with the exact factor, a conversion chart and worked steps.
- [Horsepower to kilowatts converter](https://www.calcopenly.com/conversion/hp-to-kw.md): Convert horsepower to kilowatts (hp to kW) with the exact factor, a conversion chart and worked steps.
- [Kilowatts to horsepower converter](https://www.calcopenly.com/conversion/kw-to-hp.md): Convert kilowatts to horsepower (kW to hp) with the exact factor, a conversion chart and worked steps.
- [Megabytes to gigabytes converter](https://www.calcopenly.com/conversion/mb-to-gb.md): Convert megabytes to gigabytes (MB to GB) with the exact factor, a conversion chart and worked steps.
- [Gigabytes to megabytes converter](https://www.calcopenly.com/conversion/gb-to-mb.md): Convert gigabytes to megabytes (GB to MB) with the exact factor, a conversion chart and worked steps.
- [Gigabytes to terabytes converter](https://www.calcopenly.com/conversion/gb-to-tb.md): Convert gigabytes to terabytes (GB to TB) with the exact factor, a conversion chart and worked steps.
- [Terabytes to gigabytes converter](https://www.calcopenly.com/conversion/tb-to-gb.md): Convert terabytes to gigabytes (TB to GB) with the exact factor, a conversion chart and worked steps.
- [Megabits per second to megabytes per second converter](https://www.calcopenly.com/conversion/mbps-to-mbs.md): Convert megabits per second to megabytes per second (Mbps to MB/s) with the exact factor, a conversion chart and worked steps.
- [Ounces to pounds converter](https://www.calcopenly.com/conversion/ounces-to-pounds.md): Convert ounces to pounds (oz to lbs) with the exact factor, a conversion chart and worked steps.
- [Pounds to ounces converter](https://www.calcopenly.com/conversion/pounds-to-ounces.md): Convert pounds to ounces (lbs to oz) with the exact factor, a conversion chart and worked steps.
- [Pounds to stone converter](https://www.calcopenly.com/conversion/lbs-to-stones.md): Convert pounds to stone (lbs to stone) with the exact factor, a conversion chart and worked steps.
- [Grams to kilograms converter](https://www.calcopenly.com/conversion/grams-to-kg.md): Convert grams to kilograms (grams to kg) with the exact factor, a conversion chart and worked steps.
- [Kilograms to grams converter](https://www.calcopenly.com/conversion/kg-to-grams.md): Convert kilograms to grams (kg to grams) with the exact factor, a conversion chart and worked steps.
- [US short tons to pounds converter](https://www.calcopenly.com/conversion/tons-to-pounds.md): Convert US short tons to pounds (tons to lbs) with the exact factor, a conversion chart and worked steps.
- [Metric tonnes to pounds converter](https://www.calcopenly.com/conversion/metric-tons-to-pounds.md): Convert metric tonnes to pounds (metric tons to lbs) with the exact factor, a conversion chart and worked steps.
- [Milliliters to liters converter](https://www.calcopenly.com/conversion/ml-to-liters.md): Convert milliliters to liters (ml to liters) with the exact factor, a conversion chart and worked steps.
- [Liters to milliliters converter](https://www.calcopenly.com/conversion/liters-to-ml.md): Convert liters to milliliters (liters to ml) with the exact factor, a conversion chart and worked steps.
- [US tablespoons to US teaspoons converter](https://www.calcopenly.com/conversion/tablespoons-to-teaspoons.md): Convert US tablespoons to US teaspoons (tbsp to tsp) with the exact factor, a conversion chart and worked steps.
- [US teaspoons to US tablespoons converter](https://www.calcopenly.com/conversion/teaspoons-to-tablespoons.md): Convert US teaspoons to US tablespoons (tsp to tbsp) with the exact factor, a conversion chart and worked steps.
- [US cups to US tablespoons converter](https://www.calcopenly.com/conversion/cups-to-tablespoons.md): Convert US cups to US tablespoons (cups to tbsp) with the exact factor, a conversion chart and worked steps.
- [US tablespoons to US cups converter](https://www.calcopenly.com/conversion/tablespoons-to-cups.md): Convert US tablespoons to US cups (tbsp to cups) with the exact factor, a conversion chart and worked steps.
- [US fluid ounces to US cups converter](https://www.calcopenly.com/conversion/ounces-to-cups.md): Convert US fluid ounces to US cups (oz to cups) with the exact factor, a conversion chart and worked steps.
- [Liters to US cups converter](https://www.calcopenly.com/conversion/liters-to-cups.md): Convert liters to US cups (liters to cups) with the exact factor, a conversion chart and worked steps.
- [US pints to US cups converter](https://www.calcopenly.com/conversion/pints-to-cups.md): Convert US pints to US cups (pints to cups) with the exact factor, a conversion chart and worked steps.
- [Millimeters to centimeters converter](https://www.calcopenly.com/conversion/mm-to-cm.md): Convert millimeters to centimeters (mm to cm) with the exact factor, a conversion chart and worked steps.
- [Centimeters to millimeters converter](https://www.calcopenly.com/conversion/cm-to-mm.md): Convert centimeters to millimeters (cm to mm) with the exact factor, a conversion chart and worked steps.
- [Centimeters to meters converter](https://www.calcopenly.com/conversion/cm-to-meters.md): Convert centimeters to meters (cm to meters) with the exact factor, a conversion chart and worked steps.
- [Meters to centimeters converter](https://www.calcopenly.com/conversion/meters-to-cm.md): Convert meters to centimeters (meters to cm) with the exact factor, a conversion chart and worked steps.
- [Miles to feet converter](https://www.calcopenly.com/conversion/miles-to-feet.md): Convert miles to feet (miles to feet) with the exact factor, a conversion chart and worked steps.
- [Feet to miles converter](https://www.calcopenly.com/conversion/feet-to-miles.md): Convert feet to miles (feet to miles) with the exact factor, a conversion chart and worked steps.
- [Meters per second to kilometers per hour converter](https://www.calcopenly.com/conversion/mps-to-kmh.md): Convert meters per second to kilometers per hour (m/s to km/h) with the exact factor, a conversion chart and worked steps.
- [Kilometers per hour to meters per second converter](https://www.calcopenly.com/conversion/kmh-to-mps.md): Convert kilometers per hour to meters per second (km/h to m/s) with the exact factor, a conversion chart and worked steps.
- [Newton-meters to pound-feet converter](https://www.calcopenly.com/conversion/newton-meters-to-foot-pounds.md): Convert newton-meters to pound-feet (Nm to ft-lbs) with the exact factor, a conversion chart and worked steps.
- [Pound-feet to newton-meters converter](https://www.calcopenly.com/conversion/foot-pounds-to-newton-meters.md): Convert pound-feet to newton-meters (ft-lbs to Nm) with the exact factor, a conversion chart and worked steps.
- [Degrees Celsius to degrees Fahrenheit converter](https://www.calcopenly.com/conversion/celsius-to-fahrenheit.md): Convert degrees Celsius to degrees Fahrenheit (Celsius to Fahrenheit) with the exact formula, a conversion chart and worked steps.
- [Degrees Fahrenheit to degrees Celsius converter](https://www.calcopenly.com/conversion/fahrenheit-to-celsius.md): Convert degrees Fahrenheit to degrees Celsius (Fahrenheit to Celsius) with the exact formula, a conversion chart and worked steps.
- [Degrees Celsius to kelvins converter](https://www.calcopenly.com/conversion/celsius-to-kelvin.md): Convert degrees Celsius to kelvins (Celsius to Kelvin) with the exact formula, a conversion chart and worked steps.
- [Kelvins to degrees Celsius converter](https://www.calcopenly.com/conversion/kelvin-to-celsius.md): Convert kelvins to degrees Celsius (Kelvin to Celsius) with the exact formula, a conversion chart and worked steps.
- [Degrees Fahrenheit to kelvins converter](https://www.calcopenly.com/conversion/fahrenheit-to-kelvin.md): Convert degrees Fahrenheit to kelvins (Fahrenheit to Kelvin) with the exact formula, a conversion chart and worked steps.
- [Kelvins to degrees Fahrenheit converter](https://www.calcopenly.com/conversion/kelvin-to-fahrenheit.md): Convert kelvins to degrees Fahrenheit (Kelvin to Fahrenheit) with the exact formula, a conversion chart and worked steps.
- [US miles per gallon to liters per 100 km converter](https://www.calcopenly.com/conversion/mpg-to-l-100km.md): Convert US miles per gallon to liters per 100 km (mpg to L/100km) with the exact formula, a conversion chart and worked steps.
- [Liters per 100 km to US miles per gallon converter](https://www.calcopenly.com/conversion/l-100km-to-mpg.md): Convert liters per 100 km to US miles per gallon (L/100km to mpg) with the exact formula, a conversion chart and worked steps.

## Science calculators

- [Kinematics (SUVAT) calculator](https://www.calcopenly.com/science/kinematics-calculator.md): Kinematics calculator for the SUVAT equations: enter three of displacement, initial and final velocity, acceleration and time to get the other two.
- [Projectile motion calculator](https://www.calcopenly.com/science/projectile-motion-calculator.md): Projectile motion calculator: range, maximum height, time of flight and impact speed for any launch angle and height, on Earth or other worlds, with drag.
- [F = ma calculator: force, friction and inclined plane](https://www.calcopenly.com/science/force-friction-incline-calculator.md): Solve Newton's second law F = ma for force, mass or acceleration, or find acceleration, normal force and friction for a block on an inclined plane.
- [Kinetic and potential energy, work and power calculator](https://www.calcopenly.com/science/work-energy-power-calculator.md): Kinetic energy (½mv²), potential energy (mgh), spring energy, work (Fd cos θ) and power (W/t), solved for any variable, plus the speed after a drop.
- [Momentum and collision calculator (elastic and inelastic)](https://www.calcopenly.com/science/momentum-collision-calculator.md): Momentum and collision calculator: final velocities, total momentum and kinetic energy lost in an elastic, inelastic or partly elastic head-on collision.
- [Centripetal force, moment of inertia and torque calculator](https://www.calcopenly.com/science/circular-motion-rotation-calculator.md): Centripetal force and acceleration from mass, speed and radius; rpm to rad/s and period; moment of inertia of nine shapes; torque from force and lever arm.
- [Orbital velocity and gravity calculator](https://www.calcopenly.com/science/gravity-orbit-calculator.md): Orbital velocity and period, escape velocity, surface gravity, your weight on the Moon or Mars, and the gravitational force between two masses.
- [Ohm's law calculator](https://www.calcopenly.com/science/ohms-law-calculator.md): Ohm's law calculator: enter any two of voltage, current, resistance and power to get the other two, shown in the units you pick (mA, kΩ…).
- [Resistor colour code calculator](https://www.calcopenly.com/science/resistor-color-code-calculator.md): Resistor colour code calculator for 4, 5 and 6-band resistors: colours to ohms and tolerance, or a value to its bands, snapped to E12, E24 or E96.
- [Series and parallel resistor calculator](https://www.calcopenly.com/science/series-parallel-calculator.md): Series and parallel resistor calculator: total resistance of any number of resistors, plus capacitors or inductors in series or parallel.
- [RC time constant and RLC circuit calculator](https://www.calcopenly.com/science/rc-rl-rlc-circuit-calculator.md): RC and RL time constant and the time to charge or discharge to any percent; series RLC resonant frequency, impedance, phase, Q factor and bandwidth.
- [Voltage divider and LED resistor calculator](https://www.calcopenly.com/science/voltage-divider-led-resistor-calculator.md): Voltage divider output, or R1 or R2 for a target voltage; the current-limiting resistor for LEDs with its nearest E12 value and power rating.
- [Voltage drop and AWG wire gauge calculator](https://www.calcopenly.com/science/wire-gauge-voltage-drop-calculator.md): Voltage drop over a DC, single-phase or three-phase cable run, plus AWG wire size to diameter, mm², kcmil and resistance per km, and back.
- [Electricity cost calculator](https://www.calcopenly.com/science/electricity-cost-calculator.md): Electricity cost of running an appliance per hour, day, month and year, from its wattage, hours of use and your price per kWh (unit).
- [Wavelength, frequency and photon energy calculator](https://www.calcopenly.com/science/wavelength-frequency-energy-calculator.md): Convert wavelength to frequency and photon energy, or back, with c = fλ and E = hf, and see where the wave sits in the electromagnetic spectrum.
- [Thin lens, mirror and Snell's law calculator](https://www.calcopenly.com/science/optics-lens-snell-calculator.md): Thin lens and mirror equation for image distance, object distance or focal length, with magnification; Snell's law refraction and critical angle.
- [Specific heat, latent heat and Carnot efficiency calculator](https://www.calcopenly.com/science/heat-transfer-calculator.md): Heat energy from Q = mcΔT (solve for heat, mass, final temperature or specific heat), latent heat Q = mL for melting or boiling, and Carnot efficiency.
- [Ideal gas law calculator](https://www.calcopenly.com/science/ideal-gas-law-calculator.md): Solve the ideal gas law PV = nRT for pressure, volume, moles or temperature in any units, or find a new state with the combined gas law.
- [Molar mass calculator](https://www.calcopenly.com/science/molar-mass-calculator.md): Molar mass in g/mol and mass percent composition of any chemical formula, with brackets and hydrates such as CuSO4·5H2O, from IUPAC 2021 atomic weights.
- [Grams to moles and stoichiometry calculator](https://www.calcopenly.com/science/moles-stoichiometry-calculator.md): Convert grams to moles and particles for any chemical formula, and find the limiting reagent, theoretical yield and leftover excess of a balanced reaction.
- [Dilution and molarity calculator](https://www.calcopenly.com/science/dilution-concentration-calculator.md): Solve C₁V₁ = C₂V₂ for any dilution variable, get molarity, % w/v and ppm from a weighed mass, the mass to weigh for a solution, or molality.
- [pH calculator for acids, bases and buffers](https://www.calcopenly.com/science/ph-calculator.md): Calculate pH, pOH, [H⁺] and [OH⁻] from a concentration, a strong acid or base, a weak acid's Ka or pKa, or a Henderson–Hasselbalch buffer.
- [Half-life and radioactive decay calculator](https://www.calcopenly.com/science/half-life-radioactive-decay-calculator.md): Half-life calculator: amount left, starting amount, elapsed time or half-life from N = N₀·2^(−t/t½), with carbon-14 and other isotope presets.
- [Astronomy calculator: light time, magnitudes and redshift](https://www.calcopenly.com/science/astronomy-calculator.md): Light travel time for any distance, apparent and absolute magnitude from the distance modulus, and redshift to recession velocity (relativistic Doppler).
- [Percent error and uncertainty propagation calculator](https://www.calcopenly.com/science/percent-error-propagation-calculator.md): Percent error from measured and accepted values, and uncertainty propagation through sums, products, quotients and powers, in quadrature or worst case.
- [Horsepower calculator: torque, rpm and quarter-mile](https://www.calcopenly.com/science/horsepower-calculator.md): Horsepower from torque and rpm (hp = lb-ft × rpm ÷ 5252) or from quarter-mile ET and trap speed, with crank vs wheel horsepower and drivetrain loss.

## Statistics and probability calculators

- [Descriptive statistics calculator](https://www.calcopenly.com/statistics/descriptive-statistics-calculator.md): Descriptive statistics calculator: mean, median, mode, standard deviation, variance, quartiles, IQR, outliers, skewness and kurtosis, with a histogram.
- [Grade curve calculator](https://www.calcopenly.com/statistics/grade-curve-calculator.md): Grade curve calculator: rescale a class's scores to a target mean and standard deviation, or add flat points, with z-scores and percentile ranks.
- [Normal distribution & z-score calculator](https://www.calcopenly.com/statistics/normal-distribution-calculator.md): Normal distribution calculator: z-scores, the probability below, above or between values, and the value at any percentile (inverse normal).
- [Binomial & Poisson distribution calculator](https://www.calcopenly.com/statistics/binomial-poisson-distribution-calculator.md): Binomial distribution calculator: exact P(X = k), P(X ≤ k), tails and ranges for binomial, Poisson, geometric, negative binomial and hypergeometric.
- [t, chi-square & F distribution calculator](https://www.calcopenly.com/statistics/t-chi-square-f-distribution-calculator.md): t, chi-square and F distribution calculator: tail areas, p-values, densities and critical values, plus exponential and uniform distributions.
- [Confidence interval calculator](https://www.calcopenly.com/statistics/confidence-interval-calculator.md): Confidence interval calculator for a mean (t or z), a proportion (Wilson or Wald) or a difference of two means, with the margin of error and both bounds.
- [t-test and z-test calculator](https://www.calcopenly.com/statistics/t-test-calculator.md): t-test calculator for one-sample, two-sample (Welch or pooled) and paired tests, plus z-tests for a mean or proportion: p-value, critical value, decision.
- [Chi-square test calculator](https://www.calcopenly.com/statistics/chi-square-test-calculator.md): Chi-square test calculator for goodness of fit and independence in a contingency table: χ², p-value, expected counts and Cramér's V.
- [One-way ANOVA calculator](https://www.calcopenly.com/statistics/one-way-anova-calculator.md): One-way ANOVA calculator: the F statistic, p-value, sums of squares, mean squares and η² for two or more groups, with the full ANOVA table.
- [Sample size and power calculator](https://www.calcopenly.com/statistics/sample-size-calculator.md): Sample size calculator for surveys and studies: n for a margin of error on a proportion or mean, and the per-group n for a target power.
- [Linear regression calculator (line of best fit)](https://www.calcopenly.com/statistics/regression-calculator.md): Linear regression calculator: least-squares line of best fit with R², standard errors, p-values and predictions, plus polynomial and exponential fits.
- [Correlation coefficient calculator (Pearson and Spearman)](https://www.calcopenly.com/statistics/correlation-coefficient-calculator.md): Correlation coefficient calculator: Pearson's r or Spearman's rank correlation for paired data, with r², a t statistic and a two-sided p-value.
- [Permutation and combination calculator (nPr, nCr)](https://www.calcopenly.com/statistics/permutations-combinations-calculator.md): Calculate nCr and nPr exactly: combinations and permutations with or without repetition, for poker hands, lottery odds and PIN codes.
- [Probability calculator (events & Bayes' theorem)](https://www.calcopenly.com/statistics/probability-calculator.md): Calculate P(A or B), P(A and B) and P(A | B) for two events, or apply Bayes' theorem to a test result, with a probability tree and Venn diagram.
- [Dice, coin and card probability calculator](https://www.calcopenly.com/statistics/dice-coin-card-probability-calculator.md): Exact probability of dice sums, coin-flip heads and streaks, drawing special cards from a deck and each 5-card poker hand, as a fraction and 1 in N.
- [Expected value calculator](https://www.calcopenly.com/statistics/expected-value-calculator.md): Calculate expected value E[X], variance and standard deviation for a bet, game or decision from its outcomes and their probabilities or weights.
- [Odds converter (fractional, decimal, American, probability)](https://www.calcopenly.com/statistics/odds-converter.md): Convert odds between fractional, decimal and American (moneyline) formats and get the implied probability, worked in exact fractions.
- [Random number generator (seeded)](https://www.calcopenly.com/statistics/random-number-generator.md): Generate random numbers from a seed: integers in a range, decimals, lottery-style draws without repeats and dice rolls, repeatable with xoshiro256**.

## Construction and home calculators

- [Room area and square footage calculator](https://www.calcopenly.com/construction/room-area-calculator.md): Floor area in square metres and square feet, wall area, perimeter and volume for one or more rectangular rooms or an L-shaped room.
- [Paint calculator](https://www.calcopenly.com/construction/paint-calculator.md): Paint calculator: litres, US gallons and whole cans of paint and primer for a room, from wall area minus doors and windows, coats and coverage.
- [Flooring and tile calculator](https://www.calcopenly.com/construction/tile-calculator.md): Tile calculator: tiles and boxes for a floor or wall from room size, tile size, grout joint and waste allowance, plus grout in litres and kg.
- [Concrete calculator](https://www.calcopenly.com/construction/concrete-calculator.md): Calculate concrete volume and bags for slabs, footings, columns or steps. Compare bag and ready-mix quotes with delivery fees, minimums and order increments.
- [Brick calculator: bricks, blocks and mortar](https://www.calcopenly.com/construction/brick-calculator.md): Brick calculator: bricks or blocks for a wall from its size, openings, unit size and joint, with count per m² or ft², mortar volume and waste.
- [Roofing and shingle calculator](https://www.calcopenly.com/construction/roofing-calculator.md): Roof area, squares and shingle bundles from building size and pitch, with underlayment rolls, ridge cap and the IRC minimum slope check.
- [Stair calculator](https://www.calcopenly.com/construction/stair-calculator.md): Number of steps, riser height, tread depth, stringer length and stair angle from total rise and run, checked against IRC riser and tread limits.
- [Drywall and plasterboard calculator](https://www.calcopenly.com/construction/drywall-calculator.md): Drywall sheets for a room's walls and ceiling after doors and windows, with screws, joint tape and compound, for 4 × 8 ft or metric plasterboard.
- [Board foot calculator for lumber and timber](https://www.calcopenly.com/construction/board-foot-calculator.md): Board foot calculator: board feet, linear feet, volume and cost for a stack of lumber, at nominal size and at the dressed size of a 2x4, 2x6 and more.
- [Gravel calculator for gravel, sand, soil and mulch](https://www.calcopenly.com/construction/gravel-calculator.md): Gravel calculator: cubic metres, cubic yards, tonnes, bags and truck loads of gravel, sand, topsoil or mulch for an area and depth.
- [Fence calculator](https://www.calcopenly.com/construction/fence-calculator.md): Fence calculator: posts, rails, pickets and bags of concrete for a straight fence run, from its length, post spacing, picket width and gap.
- [Deck calculator](https://www.calcopenly.com/construction/deck-calculator.md): Deck boards, joists and screws or hidden clips for a rectangular deck, from its size, joist spacing, board width, gap and waste allowance.
- [Wallpaper calculator](https://www.calcopenly.com/construction/wallpaper-calculator.md): Wallpaper calculator: rolls to buy from wall width and height, roll size, pattern repeat and trimming, counted as full-height drops per roll.
- [Electrical load and breaker size calculator](https://www.calcopenly.com/construction/electrical-load-calculator.md): Breaker size for one circuit: total watts and amps from a list of appliances, with the NEC 125% continuous-load rule and NEC or IEC breaker ratings.
- [Air conditioner BTU calculator](https://www.calcopenly.com/construction/btu-calculator.md): Air conditioner size for a room in BTU/h, tons and kW from floor area, ceiling height, insulation, sun and occupants, beside the Energy Star chart.
- [Pool volume and tank capacity calculator](https://www.calcopenly.com/construction/pool-volume-calculator.md): Pool volume in gallons, litres and m³ for rectangular, round or oval pools and water tanks, with fill time and the chlorine dose to raise ppm.
- [Solar panel calculator](https://www.calcopenly.com/construction/solar-panel-calculator.md): How many solar panels you need: system size in kW, panel count, yearly kWh, installed cost and payback from your use and peak sun hours.
- [Trip fuel cost calculator](https://www.calcopenly.com/construction/fuel-cost-calculator.md): Fuel cost of a trip from distance, mpg or L/100 km and fuel price, with tolls, a round-trip option and the cost split per person.
- [EV charging cost and time calculator](https://www.calcopenly.com/construction/ev-charging-calculator.md): EV charging cost and time between two battery levels at any charger power, with range added and cost per 100 km or miles against petrol.
- [Car ownership cost calculator](https://www.calcopenly.com/construction/car-ownership-cost-calculator.md): Total cost of owning a car over 1–15 years: depreciation, fuel, insurance, maintenance and loan interest, per year, per km and per mile.

## Everyday calculators

- [Tip calculator and bill splitter](https://www.calcopenly.com/everyday/tip-and-bill-split-calculator.md): Tip calculator for any bill: tip on the pre-tax or after-tax total, then split it evenly or by shares, with each person's share rounded up.
- [Discount, markup and margin calculator](https://www.calcopenly.com/everyday/discount-and-markup-calculator.md): Sale price after one or more percent-off discounts, and selling price from cost using a markup or a profit margin, with each converted to the other.
- [Unit price comparison calculator](https://www.calcopenly.com/everyday/unit-price-comparison-calculator.md): Unit price calculator: compare up to four pack sizes by price per kg, litre, 100 g, ounce or item to see which is cheapest and by how much.
- [Recipe scaler](https://www.calcopenly.com/everyday/recipe-scaler.md): Scale a recipe to any number of servings: each ingredient is multiplied by new ÷ original servings, with cups and spoons shown as kitchen fractions.
- [Oven temperature and pan size converter](https://www.calcopenly.com/everyday/oven-temperature-and-pan-size-converter.md): Convert oven temperatures between °C, °F, fan oven and gas mark, and work out how much to scale a recipe for a different round, square or rectangular pan.
- [Grade calculator](https://www.calcopenly.com/everyday/grade-calculator.md): Grade calculator for weighted categories: your current course grade, and the score you need on the final exam or remaining work to reach a target.
- [GPA calculator](https://www.calcopenly.com/everyday/gpa-calculator.md): GPA calculator: credit-weighted grade point average on the 4.0 scale from letter grades, plus percentage-to-GPA and CBSE CGPA-to-percentage conversions.
- [Word counter and reading time calculator](https://www.calcopenly.com/everyday/word-count-and-reading-time.md): Word counter: words, characters with and without spaces, sentences and paragraphs, plus reading time at 238 wpm and speaking time at 150 wpm.
- [PPI calculator for screen size and aspect ratio](https://www.calcopenly.com/everyday/screen-size-ppi-calculator.md): PPI calculator: pixel density from resolution and diagonal, plus screen width and height, aspect ratio, dot pitch and the distance where pixels blend.
- [Dog years and cat years calculator](https://www.calcopenly.com/everyday/dog-and-cat-age-in-human-years.md): Dog years and cat years calculator: a pet's age in human years from the AAHA/Zoetis size chart or the International Cat Care table, for fun comparisons.
- [Group expense splitter for trips and parties](https://www.calcopenly.com/everyday/trip-expense-splitter.md): Expense splitter: enter who paid what to get each person's equal share and who owes whom, settled with the fewest possible payments.
- [Travel budget and jet lag calculator](https://www.calcopenly.com/everyday/travel-budget-and-jet-lag-calculator.md): Trip budget from daily spending per person, fixed costs and a contingency, plus how many days of jet lag to expect after crossing time zones.
- [Tire size and speedometer calculator](https://www.calcopenly.com/everyday/tire-size-and-speedometer-calculator.md): Tire diameter, sidewall height and revolutions per km from a size such as 225/45R17, and the speedometer error when you change tire sizes.
- [Love calculator (just for fun)](https://www.calcopenly.com/everyday/love-compatibility-calculator.md): For entertainment only: a love compatibility score from 0 to 100 made from two names. The same pair always gets the same score; it predicts nothing.
- [Case converter: title, sentence, upper and lower case](https://www.calcopenly.com/everyday/case-converter.md): Convert text to title case, sentence case, UPPER or lower case, or to camelCase, snake_case and kebab-case, with character and word counts.
- [Wedding and event budget calculator](https://www.calcopenly.com/everyday/wedding-and-event-budget-calculator.md): Split a wedding or event budget across categories by percentage or fixed amount, with the cost per guest and what is left to allocate.
- [Gas mileage calculator (MPG calculator)](https://www.calcopenly.com/everyday/gas-mileage-calculator.md): Gas mileage calculator: MPG (US and UK), L/100 km and km/L from odometer readings and fuel added, cost per mile, and a fill-up log with trend chart.
- [Bra size calculator](https://www.calcopenly.com/everyday/bra-size-calculator.md): Bra size calculator: band and cup from underbust and bust in inches or cm, in US, UK, EU, FR/BE and AU sizes, with sister sizes and the method stated.
- [Golf handicap calculator (World Handicap System)](https://www.calcopenly.com/everyday/golf-handicap-calculator.md): Golf handicap calculator: World Handicap System Handicap Index from your score differentials (best 8 of 20), then course and playing handicap for any tee.

## Programming and tech calculators

- [Binary, hex and decimal converter](https://www.calcopenly.com/programming/binary-hex-converter.md): Convert numbers between binary, decimal, hex, octal and any base 2–36, including fractions, repeating digits and two's-complement bits for negatives.
- [Bitwise calculator (AND, OR, XOR, NOT and shifts)](https://www.calcopenly.com/programming/bitwise-calculator.md): Bitwise AND, OR, XOR, NOT, NAND, NOR, shifts and rotates on 8- to 64-bit integers, shown in decimal, hex and binary with a bit-by-bit grid.
- [Big-O time complexity calculator](https://www.calcopenly.com/programming/big-o-growth-calculator.md): Operation counts and running times for O(1), O(log n), O(n), O(n log n), O(n²), O(n³), O(2ⁿ) and O(n!) at your input size, on a log-scale chart.
- [Hash generator and checksum calculator (MD5, SHA-256)](https://www.calcopenly.com/programming/hash-checksum-calculator.md): Generate MD5, SHA-1, SHA-256, SHA-512 and CRC-32 hashes of any text, check them against a published checksum, and see the avalanche effect.
- [Base64, URL and HTML encoder and decoder](https://www.calcopenly.com/programming/text-encoder-decoder.md): Encode or decode Base64, URL-safe Base64, URL percent-encoding, HTML entities, hex bytes and Unicode code points, with UTF-8 and UTF-16 byte counts.
- [UUID generator and decoder (v4, v7)](https://www.calcopenly.com/programming/uuid-decoder-generator.md): Generate reproducible UUID v4 and v7 values from a seed, or validate any UUID or GUID and decode its version, variant and embedded timestamp.
- [JSON formatter and validator](https://www.calcopenly.com/programming/json-formatter-validator.md): Format (pretty-print) or minify JSON and validate it against RFC 8259, with the line and column of any syntax error explained in plain words.
- [Color code converter (HEX, RGB, HSL, CMYK, OKLCH)](https://www.calcopenly.com/programming/color-code-converter.md): Convert a color from HEX to RGB, HSL, HSV, CMYK, CIE Lab and OKLCH or back, and find its nearest CSS named color and relative luminance.
- [Color contrast checker (WCAG 2.2)](https://www.calcopenly.com/programming/wcag-contrast-checker.md): Check the WCAG 2.2 contrast ratio between a text color and its background, with AA and AAA pass or fail for normal text, large text and UI parts.
- [Color palette generator (complementary, triadic, analogous)](https://www.calcopenly.com/programming/color-palette-generator.md): Generate complementary, analogous, triadic, split-complementary, tetradic or monochromatic color palettes from one base color, with HEX codes.
- [Color blindness simulator](https://www.calcopenly.com/programming/color-blindness-simulator.md): How a color looks with protanopia, deuteranopia or tritanopia (red, green or blue color blindness), using the Machado et al. (2009) model.
- [Aspect ratio calculator (16:9, 4:3, 21:9)](https://www.calcopenly.com/programming/aspect-ratio-resolution-calculator.md): Find the aspect ratio of any resolution, such as 1920 × 1080 = 16:9, resize it to a new width or height, or fit it in a screen with letterbox bars.
- [Subnet calculator (IPv4 and IPv6 CIDR)](https://www.calcopenly.com/programming/subnet-cidr-calculator.md): Find the network address, broadcast, usable host range and host count of any IPv4 or IPv6 CIDR block, with netmask, wildcard and equal subnets.
- [RAID calculator (RAID 0, 1, 5, 6 and 10)](https://www.calcopenly.com/programming/raid-storage-calculator.md): Calculate usable RAID capacity, parity or mirror overhead and how many drive failures RAID 0, 1, 5, 6 and 10 survive, in TB and the TiB Windows shows.
- [Bandwidth and download time calculator](https://www.calcopenly.com/programming/bandwidth-data-transfer-calculator.md): Download or upload time for a file at a given speed, the data a link moves in a set time, and a website's monthly bandwidth from page views.
- [Password strength checker and generator](https://www.calcopenly.com/programming/password-strength-generator.md): Check a password's entropy in bits and its average brute-force crack time at a chosen guess rate, or generate a password from a reproducible seed.
- [Cron expression parser and explainer](https://www.calcopenly.com/programming/cron-expression-parser.md): Translate a five-field cron expression or crontab line into plain English and list its next run times after any start date and time, in UTC.

## Weather, earth and fun calculators

- [Moon phase calculator](https://www.calcopenly.com/earth/moon-phase-calculator.md): Moon phase for any date and time: the phase name, percentage illuminated and moon age in days, with the dates of the next new and full moons.
- [Wind chill, heat index and dew point calculator](https://www.calcopenly.com/earth/wind-chill-heat-index-dew-point.md): Wind chill and heat index calculator: the feels-like temperature from the NWS formulas, plus dew point, frostbite risk and heat-stress level.
- [Air pressure at altitude and boiling point calculator](https://www.calcopenly.com/earth/altitude-air-pressure-boiling-point.md): Air pressure at altitude from the standard atmosphere, with temperature, air density and the boiling point of water, or the altitude for a given pressure.
- [Personal carbon footprint calculator](https://www.calcopenly.com/earth/carbon-footprint-calculator.md): Carbon footprint calculator: yearly tonnes of CO₂e from driving, flights, train and bus, home electricity and diet, using UK government emission factors.
- [Rainwater harvesting calculator](https://www.calcopenly.com/earth/rainwater-harvesting-calculator.md): Rainwater harvesting calculator: yearly litres or gallons a roof collects from its area, rainfall and efficiency, and the share of household use it covers.
- [Zodiac sign calculator: star sign and Chinese zodiac](https://www.calcopenly.com/earth/zodiac-sign-calculator.md): Zodiac sign calculator: your star sign and its element from a birth date, plus the Chinese zodiac animal, element and yin or yang. For entertainment.
- [Life path number calculator (numerology)](https://www.calcopenly.com/earth/life-path-number-calculator.md): Life path number calculator: a birth date reduced to a numerology number from 1 to 9, or the master numbers 11, 22 and 33, with every step shown.

## About

- [How CalcOpenly calculates](https://www.calcopenly.com/about): precision, rounding, verification and privacy.