359 free online calculators

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

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

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

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.

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.

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.

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

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.

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.

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

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.