Calculators

Percentage, percentage difference, age, chronological age and date calculators, plus a unit converter with exact factors. Free, no sign-up.

Percentage CalculatorWork out X% of Y, X as a percentage of Y, an increase or decrease by a percentage, and the percentage change between two numbers.
Percentage Difference CalculatorFind the percentage difference between two values, with the absolute difference and the percentage change in each direction.
Age CalculatorFind an exact age in years, months and days on any date, with totals in months, weeks and days and the countdown to the next birthday.
Chronological Age CalculatorWork out a chronological age in years, months and days on a test date, by calendar months or the 30-day borrowing method, with optional rounding.
Date CalculatorCount the days, weeks, months and business days between two dates, or add and subtract days, weeks, months or years from a date.
Unit ConverterConvert length, weight, temperature, area, volume (US and UK), speed, time, data storage and pressure units with exact conversion factors.