All calculators

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.

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.

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.

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.

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.

Add, subtract, multiply and divide fractions and mixed numbers exactly, simplify to lowest terms, and convert decimals (including repeating) to fractions.

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.

Plot several functions, polar curves and parametric curves; pan and zoom; find roots, intersections, turning points and areas.

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.

Long division calculator that shows every step: quotient and remainder, the decimal quotient with its repeating block marked, and the fraction.

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.

Average calculator for a list of numbers: mean, median, mode, range, count and sum, with the sorted data and the middle values highlighted.

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.

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.

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.

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.

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.

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.

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.

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.

Round a number to decimal places, significant figures or the nearest ten or hundred under nine rules, including banker's rounding, floor and ceiling.

Keypad calculator with trig in degrees, radians or gradians, logs, powers, factorials, memory and a history tape: exact fractions where possible.

Scientific notation calculator: convert between decimal, scientific, E and engineering notation, and add, subtract, multiply or divide with sig-fig rules.

Union, intersection, differences and symmetric difference of two sets of numbers or words, with the Jaccard index and a Venn diagram.

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.

Solve 2 to 5 simultaneous linear equations exactly by Gauss–Jordan elimination, with every row operation shown, and detect no-solution or infinite cases.

Truth table of a Boolean expression in up to 6 variables, with the canonical sum of products, product of sums, minterms and maxterms.

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.

Weighted average calculator: enter values with weights, one pair per line, for the weighted mean, sum of weights and each value's contribution.

Convert angles between decimal degrees, degrees-minutes-seconds (DMS), radians, gradians, turns, arcminutes, arcseconds and milliradians.

Area and perimeter of 15 plane shapes, from rectangles, triangles and trapezoids to circles, ellipses, regular polygons and rings, drawn to scale.

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.

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.

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.

Area, perimeter and centroid of any simple polygon from its vertex coordinates, using the shoelace (surveyor's) formula with every term shown.

Hypotenuse, missing leg, both acute angles, area and perimeter of a right triangle from any two values, using Pythagoras' theorem and SOHCAHTOA.

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.

Distance, midpoint and slope between two points, the line's equation in slope-intercept, standard and point-slope form, and where two lines meet.

Missing sides, angles, area, perimeter, heights, inradius and circumradius of any triangle from three measurements, with both SSA answers.

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.

Volume, surface area, slant height and capacity in litres for 14 solids, including cylinders, cones, spheres, pyramids, prisms, tori and ellipsoids.

Calculate your 401(k) balance at retirement from salary, contribution rate and a two-tier employer match, with 2026 IRS limits and catch-up.

Amortization calculator: payment, dated schedule and yearly totals for monthly, biweekly or weekly payments, with principal and interest in each.

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.

Calculate a loan's APR with fees by the Regulation Z actuarial method, the amount financed, the finance charge and the effective annual rate.

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.

Calculate European call and put prices and the Greeks (delta, gamma, theta, vega, rho) with the Black-Scholes-Merton model, including dividends.

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.

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.

Canadian mortgage payment with semi-annual compounding, accelerated bi-weekly or weekly options, the CMHC insurance premium and the balance at renewal.

Calculate a monthly car lease payment from the price, residual value and money factor or APR, split into depreciation, finance charge and tax.

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.

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.

Calculate compound interest: the future value of a deposit plus regular contributions at any compounding frequency, including daily and continuous.

Calculate how long a credit card balance takes to pay off on minimum payments versus a fixed monthly payment, and the interest each costs.

Convert between 160 currencies at the latest daily reference rates, with the rate date and a 90-day history chart.

Calculate enterprise value, equity value and value per share with a DCF: projected free cash flows plus a Gordon-growth terminal value.

Debt consolidation calculator: compare your debts with one loan; monthly payment, total interest, payoff time, APR with fees and the break-even rate.

Compare the debt snowball (smallest balance first) and avalanche (highest rate first): months to debt-free, total interest and payoff order.

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.

Calculate a depreciation schedule by straight-line, declining balance, double declining, sum-of-years' digits or units of production, with book value.

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.

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.

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.

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.

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.

Calculate income tax for India FY 2026-27 (new vs old regime), US federal 2026 and UK 2026-27, with take-home pay and marginal and effective rates.

Calculate what a purchase will cost after inflation, what your money will still buy, and your real return after inflation.

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.

Calculate the EMI on a home, car or personal loan, the total interest, and a month-by-month amortization schedule with prepayments.

Estimate your monthly mortgage payment with property tax, insurance, HOA and PMI, plus the amortization schedule and savings from extra payments.

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.

Calculate NPV, IRR, modified IRR, payback and discounted payback for a series of periodic cash flows, with the NPV profile across rates.

Calculate US take-home pay per paycheck and per year: 2026 federal withholding (IRS Pub. 15-T), Social Security, Medicare, state tax and deductions.

Compare refinancing at your planned sale or payoff month. See payments, closing costs, remaining balances and savings with cash or financed fees.

Compare renting and buying a home: net worth from owning versus renting and investing the difference, year by year, and when buying pulls ahead.

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.

Calculate how much you need to retire on inflation-adjusted expenses, the monthly saving that gets you there, and how the money runs down.

Calculate your required minimum distribution from the IRS Uniform Lifetime or joint table, your RMD starting age (73 or 75), and future RMDs.

Calculate ROI (total return) and CAGR (compound annual growth rate) from an investment's start and end values, over years or between two dates.

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.

Convert an annual salary to an hourly wage or hourly pay to salary, plus daily, weekly, biweekly, semimonthly and monthly pay.

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.

Calculate simple interest (I = P × r × t) and the maturity amount on a principal for a term in years, months or days.

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.

Calculate your average cost per share across several buys, unrealized profit and return, and the position size for your risk and stop loss.

Student loan calculator: payment, total interest and payoff date on the federal standard, tiered or extended plan or a custom term, with extra payments.

Solve for the future value, present value, interest rate or time of a lump sum from the other three, with any compounding, including continuous.

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.

Calculate XIRR, the annualized return on cash flows made on irregular dates, and XNPV at your discount rate, matching Excel's actual/365 method.

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.

Blood alcohol content (BAC) estimate by the Widmark formula from drinks, body weight and time, with the elimination curve and time back to zero.

Blood pressure category (AHA/ACC) for a systolic/diastolic reading, from normal to stage 2 and severe hypertension, with pulse pressure and MAP.

Glucose from mg/dL to mmol/L and back, and HbA1c to estimated average glucose (eAG) and IFCC mmol/mol, with ADA categories.

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.

Basal metabolic rate (BMR) by Mifflin-St Jeor, Harris-Benedict or Katch-McArdle, and daily calorie needs (TDEE) for five activity levels.

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.

Body surface area (BSA) in m² from height and weight by the Mosteller, DuBois and Haycock formulas, with the spread between them.

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.

Daily calorie target for losing, maintaining or gaining weight, with macros in grams of protein, carbohydrate and fat per day and per meal.

Calories burned by an activity from its MET value in the Compendium of Physical Activities, your body weight and the time spent.

Estimated conception date and fertile window from a due date, the last period or an ultrasound, with the likely range for each dating method.

Cycling power-to-weight (W/kg), speed and pace, or swimming pace per 100 m and 100 yd with your SWOLF score.

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.

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.

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.

Ideal body weight (IBW) for your height and sex by the Devine, Robinson, Miller and Hamwi formulas, with the healthy BMI weight range.

Lean body mass (LBM) from height, weight and sex by the Boer, James and Hume formulas, with the implied body fat percentage.

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 %.

Ovulation date, fertile window and next period for the coming cycles, from the first day of your last period and your cycle length.

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.

Pregnancy due date from the last period, conception date or IVF transfer, with today's gestational age, trimester and milestones (ACOG).

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.

Daily protein intake in grams from body weight, goal and training level, using published g/kg ranges, with a per-meal split.

Running pace per km or mile from distance and time, or finish time or distance from pace, with even splits and Riegel race predictions.

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.

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.

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.

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.

Daily water intake in litres, glasses and fl oz from body weight, exercise and climate, compared with EFSA and US adequate intakes.

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.

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.

The deadline N business days after or before a start date, skipping weekends and the holidays you list, with the calendar days it spans.

Convert a Gregorian date to Hijri (Umm al-Qura and tabular), Hebrew, Persian, Indian national (Saka) and Julian dates, or a Julian date back.

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.

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.

Days between two dates, also as years, months and days, weeks and hours, plus business days after weekends and your own holidays.

Calculate work hours, breaks and weekly timesheets. Use dates and a time zone for overnight shifts across daylight-saving changes and repeated hours.

Leap year checker: whether a year has 366 days under the Gregorian rule, which test decides it, and the previous and next leap years.

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.

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.

Add and subtract hours, minutes and seconds from a list of durations, with the total as H:MM:SS, decimal hours, minutes and seconds.

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.

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 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.

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.

Convert acres to hectares (acres to hectares) with the exact factor, a conversion chart and worked steps.

Convert acres to square feet (acres to sq ft) with the exact factor, a conversion chart and worked steps.

Convert degrees to radians and radians to degrees, plus gradians, arcminutes, arcseconds, turns and milliradians, with π carried to 50 digits.

Convert square feet to square metres, acres to hectares and sq ft to Indian land units (guntha, cent, bigha, marla, kanal, ground), with stated conversion factors.

Convert bar to psi (bar to psi) with the exact factor, a conversion chart and worked steps.

Convert centimeters to feet (cm to feet) with the exact factor, a conversion chart and worked steps.

Convert centimeters to inches (cm to inches) with the exact factor, a conversion chart and worked steps.

Convert centimeters to meters (cm to meters) with the exact factor, a conversion chart and worked steps.

Convert centimeters to millimeters (cm to mm) with the exact factor, a conversion chart and worked steps.

Convert clothing sizes between US, UK, EU, German, Italian and Japanese labels for women's dresses and tops, men's suits and shirt collars.

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.

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.

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.

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.

Convert degrees Celsius to degrees Fahrenheit (Celsius to Fahrenheit) with the exact formula, a conversion chart and worked steps.

Convert degrees Celsius to kelvins (Celsius to Kelvin) with the exact formula, a conversion chart and worked steps.

Convert degrees Fahrenheit to degrees Celsius (Fahrenheit to Celsius) with the exact formula, a conversion chart and worked steps.

Convert degrees Fahrenheit to kelvins (Fahrenheit to Kelvin) with the exact formula, a conversion chart and worked steps.

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.

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.

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.

Convert feet to centimeters (feet to cm) with the exact factor, a conversion chart and worked steps.

Convert feet to inches (feet to inches) with the exact factor, a conversion chart and worked steps.

Convert feet to meters (feet to meters) with the exact factor, a conversion chart and worked steps.

Convert feet to miles (feet to miles) with the exact factor, a conversion chart and worked steps.

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.

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.

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.

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.

Convert gigabytes to megabytes (GB to MB) with the exact factor, a conversion chart and worked steps.

Convert gigabytes to terabytes (GB to TB) with the exact factor, a conversion chart and worked steps.

Convert grams to kilograms (grams to kg) with the exact factor, a conversion chart and worked steps.

Convert grams to ounces (grams to ounces) with the exact factor, a conversion chart and worked steps.

Convert grams to pounds (grams to pounds) with the exact factor, a conversion chart and worked steps.

Convert hectares to acres (hectares to acres) with the exact factor, a conversion chart and worked steps.

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.

Convert horsepower to kilowatts (hp to kW) with the exact factor, a conversion chart and worked steps.

Convert inches to centimeters (inches to cm) with the exact factor, a conversion chart and worked steps.

Convert inches to feet (inches to feet) with the exact factor, a conversion chart and worked steps.

Convert inches to millimeters (inches to mm) with the exact factor, a conversion chart and worked steps.

Convert kelvins to degrees Celsius (Kelvin to Celsius) with the exact formula, a conversion chart and worked steps.

Convert kelvins to degrees Fahrenheit (Kelvin to Fahrenheit) with the exact formula, a conversion chart and worked steps.

Convert kilocalories to kilojoules (kcal to kJ) with the exact factor, a conversion chart and worked steps.

Convert kilograms to grams (kg to grams) with the exact factor, a conversion chart and worked steps.

Convert kilograms to pounds (kg to lbs) with the exact factor, a conversion chart and worked steps.

Convert kilograms to stone (kg to stone) with the exact factor, a conversion chart and worked steps.

Convert kilojoules to kilocalories (kJ to kcal) with the exact factor, a conversion chart and worked steps.

Convert kilometers per hour to meters per second (km/h to m/s) with the exact factor, a conversion chart and worked steps.

Convert kilometers per hour to miles per hour (km/h to mph) with the exact factor, a conversion chart and worked steps.

Convert kilometers to miles (km to miles) with the exact factor, a conversion chart and worked steps.

Convert kilopascals to psi (kPa to psi) with the exact factor, a conversion chart and worked steps.

Convert kilowatts to horsepower (kW to hp) with the exact factor, a conversion chart and worked steps.

Convert knots to miles per hour (knots to mph) with the exact factor, a conversion chart and worked steps.

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.

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.

Convert liters per 100 km to US miles per gallon (L/100km to mpg) with the exact formula, a conversion chart and worked steps.

Convert liters to milliliters (liters to ml) with the exact factor, a conversion chart and worked steps.

Convert liters to US cups (liters to cups) with the exact factor, a conversion chart and worked steps.

Convert liters to US gallons (liters to gallons) with the exact factor, a conversion chart and worked steps.

Convert megabits per second to megabytes per second (Mbps to MB/s) with the exact factor, a conversion chart and worked steps.

Convert megabytes to gigabytes (MB to GB) with the exact factor, a conversion chart and worked steps.

Convert meters per second to kilometers per hour (m/s to km/h) with the exact factor, a conversion chart and worked steps.

Convert meters to centimeters (meters to cm) with the exact factor, a conversion chart and worked steps.

Convert meters to feet (meters to feet) with the exact factor, a conversion chart and worked steps.

Convert meters to inches (meters to inches) with the exact factor, a conversion chart and worked steps.

Convert meters to yards (meters to yards) with the exact factor, a conversion chart and worked steps.

Convert metric tonnes to pounds (metric tons to lbs) with the exact factor, a conversion chart and worked steps.

Convert miles per hour to kilometers per hour (mph to km/h) with the exact factor, a conversion chart and worked steps.

Convert miles to feet (miles to feet) with the exact factor, a conversion chart and worked steps.

Convert miles to kilometers (miles to km) with the exact factor, a conversion chart and worked steps.

Convert milliliters to liters (ml to liters) with the exact factor, a conversion chart and worked steps.

Convert milliliters to US cups (ml to cups) with the exact factor, a conversion chart and worked steps.

Convert milliliters to US fluid ounces (ml to oz) with the exact factor, a conversion chart and worked steps.

Convert millimeters to centimeters (mm to cm) with the exact factor, a conversion chart and worked steps.

Convert millimeters to inches (mm to inches) with the exact factor, a conversion chart and worked steps.

Convert newton-meters to pound-feet (Nm to ft-lbs) with the exact factor, a conversion chart and worked steps.

Convert ounces to grams (ounces to grams) with the exact factor, a conversion chart and worked steps.

Convert ounces to pounds (oz to lbs) with the exact factor, a conversion chart and worked steps.

Convert pound-feet to newton-meters (ft-lbs to Nm) with the exact factor, a conversion chart and worked steps.

Convert pounds to kilograms (lbs to kg) with the exact factor, a conversion chart and worked steps.

Convert pounds to ounces (lbs to oz) with the exact factor, a conversion chart and worked steps.

Convert pounds to stone (lbs to stone) with the exact factor, a conversion chart and worked steps.

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.

Convert psi to bar, bar to psi, kPa, atm, hPa, mmHg and inHg for tyre, weather and blood pressure readings. The factor chain identifies exact definitions and the conventional approximate inHg model.

Convert psi to bar (psi to bar) with the exact factor, a conversion chart and worked steps.

Convert psi to kilopascals (psi to kPa) with the exact factor, a conversion chart and worked steps.

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.

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.

Convert mph to km/h, km/h to mph, m/s, knots and ft/s with exact factors. Includes exact vacuum light speed and an approximate Mach model at sea level.

Convert square feet to acres (sq ft to acres) with the exact factor, a conversion chart and worked steps.

Convert square feet to square meters (sq ft to sq m) with the exact factor, a conversion chart and worked steps.

Convert square meters to square feet (sq m to sq ft) with the exact factor, a conversion chart and worked steps.

Convert stone to kilograms (stone to kg) with the exact factor, a conversion chart and worked steps.

Convert stone to pounds (stone to lbs) with the exact factor, a conversion chart and worked steps.

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.

Convert terabytes to gigabytes (TB to GB) with the exact factor, a conversion chart and worked steps.

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.

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.

Convert US cups to milliliters (cups to ml) with the exact factor, a conversion chart and worked steps.

Convert US cups to US fluid ounces (cups to oz) with the exact factor, a conversion chart and worked steps.

Convert US cups to US tablespoons (cups to tbsp) with the exact factor, a conversion chart and worked steps.

Convert US fluid ounces to milliliters (oz to ml) with the exact factor, a conversion chart and worked steps.

Convert US fluid ounces to US cups (oz to cups) with the exact factor, a conversion chart and worked steps.

Convert US gallons to liters (gallons to liters) with the exact factor, a conversion chart and worked steps.

Convert US miles per gallon to liters per 100 km (mpg to L/100km) with the exact formula, a conversion chart and worked steps.

Convert US pints to US cups (pints to cups) with the exact factor, a conversion chart and worked steps.

Convert US quarts to liters (quarts to liters) with the exact factor, a conversion chart and worked steps.

Convert US short tons to pounds (tons to lbs) with the exact factor, a conversion chart and worked steps.

Convert US tablespoons to milliliters (tablespoons to ml) with the exact factor, a conversion chart and worked steps.

Convert US tablespoons to US cups (tbsp to cups) with the exact factor, a conversion chart and worked steps.

Convert US tablespoons to US teaspoons (tbsp to tsp) with the exact factor, a conversion chart and worked steps.

Convert US teaspoons to milliliters (teaspoons to ml) with the exact factor, a conversion chart and worked steps.

Convert US teaspoons to US tablespoons (tsp to tbsp) with the exact factor, a conversion chart and worked steps.

Convert gallons to litres, cups to mL and fl oz to mL exactly, with US and imperial gallons, pints and fluid ounces kept separate.

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.

Convert yards to meters (yards to meters) with the exact factor, a conversion chart and worked steps.

Light travel time for any distance, apparent and absolute magnitude from the distance modulus, and redshift to recession velocity (relativistic Doppler).

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.

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.

Electricity cost of running an appliance per hour, day, month and year, from its wattage, hours of use and your price per kWh (unit).

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.

Convert grams to moles and particles for any chemical formula, and find the limiting reagent, theoretical yield and leftover excess of a balanced reaction.

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.

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.

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.

Kinematics calculator for the SUVAT equations: enter three of displacement, initial and final velocity, acceleration and time to get the other two.

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.

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.

Momentum and collision calculator: final velocities, total momentum and kinetic energy lost in an elastic, inelastic or partly elastic head-on collision.

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…).

Orbital velocity and period, escape velocity, surface gravity, your weight on the Moon or Mars, and the gravitational force between two masses.

Percent error from measured and accepted values, and uncertainty propagation through sums, products, quotients and powers, in quadrature or worst case.

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.

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.

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.

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: total resistance of any number of resistors, plus capacitors or inductors in series or parallel.

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.

Thin lens and mirror equation for image distance, object distance or focal length, with magnification; Snell's law refraction and critical angle.

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 over a DC, single-phase or three-phase cable run, plus AWG wire size to diameter, mm², kcmil and resistance per km, and back.

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.

Binomial distribution calculator: exact P(X = k), P(X ≤ k), tails and ranges for binomial, Poisson, geometric, negative binomial and hypergeometric.

Chi-square test calculator for goodness of fit and independence in a contingency table: χ², p-value, expected counts and Cramér's V.

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.

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.

Descriptive statistics calculator: mean, median, mode, standard deviation, variance, quartiles, IQR, outliers, skewness and kurtosis, with a histogram.

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.

Calculate expected value E[X], variance and standard deviation for a bet, game or decision from its outcomes and their probabilities or weights.

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.

Linear regression calculator: least-squares line of best fit with R², standard errors, p-values and predictions, plus polynomial and exponential fits.

Normal distribution calculator: z-scores, the probability below, above or between values, and the value at any percentile (inverse normal).

Convert odds between fractional, decimal and American (moneyline) formats and get the implied probability, worked in exact fractions.

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.

Calculate nCr and nPr exactly: combinations and permutations with or without repetition, for poker hands, lottery odds and PIN codes.

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.

Generate random numbers from a seed: integers in a range, decimals, lottery-style draws without repeats and dice rolls, repeatable with xoshiro256**.

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.

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.

t, chi-square and F distribution calculator: tail areas, p-values, densities and critical values, plus exponential and uniform distributions.

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.

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.

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.

Total cost of owning a car over 1–15 years: depreciation, fuel, insurance, maintenance and loan interest, per year, per km and per mile.

Calculate concrete volume and bags for slabs, footings, columns or steps. Compare bag and ready-mix quotes with delivery fees, minimums and order increments.

Deck boards, joists and screws or hidden clips for a rectangular deck, from its size, joist spacing, board width, gap and waste allowance.

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.

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.

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.

Fence calculator: posts, rails, pickets and bags of concrete for a straight fence run, from its length, post spacing, picket width and gap.

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.

Gravel calculator: cubic metres, cubic yards, tonnes, bags and truck loads of gravel, sand, topsoil or mulch for an area and depth.

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.

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.

Roof area, squares and shingle bundles from building size and pitch, with underlayment rolls, ridge cap and the IRC minimum slope check.

Floor area in square metres and square feet, wall area, perimeter and volume for one or more rectangular rooms or an L-shaped room.

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.

Number of steps, riser height, tread depth, stringer length and stair angle from total rise and run, checked against IRC riser and tread limits.

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.

Wallpaper calculator: rolls to buy from wall width and height, roll size, pattern repeat and trimming, counted as full-height drops per roll.

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.

Convert text to title case, sentence case, UPPER or lower case, or to camelCase, snake_case and kebab-case, with character and word counts.

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.

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.

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.

Golf handicap calculator: World Handicap System Handicap Index from your score differentials (best 8 of 20), then course and playing handicap for any tee.

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.

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.

Split group expenses equally and see who pays whom. Find the fewest payments for up to 16 non-zero balances, with an approximate plan for larger groups.

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.

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.

PPI calculator: pixel density from resolution and diagonal, plus screen width and height, aspect ratio, dot pitch and the distance where pixels blend.

Scale a recipe to any number of servings: each ingredient is multiplied by new ÷ original servings, with cups and spoons shown as kitchen fractions.

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.

Tire diameter, sidewall height and revolutions per km from a size such as 225/45R17, and the speedometer error when you change tire sizes.

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.

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.

Split a wedding or event budget across categories by percentage or fixed amount, with the cost per guest and what is left to allocate.

Word counter: words, characters with and without spaces, sentences and paragraphs, plus reading time at 238 wpm and speaking time at 150 wpm.

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.

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.

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.

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.

Convert numbers between binary, decimal, hex, octal and any base 2–36, including fractions, repeating digits and two's-complement bits for negatives.

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.

How a color looks with protanopia, deuteranopia or tritanopia (red, green or blue color blindness), using the Machado et al. (2009) model.

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.

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.

Generate complementary, analogous, triadic, split-complementary, tetradic or monochromatic color palettes from one base color, with HEX codes.

Explain a five-field cron expression and list its next run times after any start date and time, in UTC.

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.

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.

Estimate character-pool entropy and brute-force search time under a random-character model, or generate reproducible sample passwords for learning.

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.

Find the network address, broadcast, usable host range and host count of any IPv4 or IPv6 CIDR block, with netmask, wildcard and equal subnets.

Generate reproducible UUID v4 and v7 values from a seed, or validate any UUID or GUID and decode its version, variant and embedded timestamp.

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.

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.

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.

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: yearly litres or gallons a roof collects from its area, rainfall and efficiency, and the share of household use it covers.

Wind chill and heat index calculator: the feels-like temperature from the NWS formulas, plus dew point, frostbite risk and heat-stress level.

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.