Everyday Math

Quick answers for everyday numbers: percentages, tips, dates, time worked, ages, and unit conversions.

Try it here: Percentage Calculator

Turn on JavaScript to use this calculator. The formula is explained below so you can work it out by hand.

Percentage CalculatorFind a percent of a number, what percent one number is of another, or the percent change.
Discount CalculatorSee the sale price and how much you save, including stacked discounts and sales tax.
Simple Interest CalculatorCalculate simple interest on a loan or deposit.
Age CalculatorFind exact age in years, months, and days, and the days until the next birthday.
Date Difference CalculatorCount the days, weeks, and weekdays between two dates.
Time Duration CalculatorFind the hours and minutes between two times, minus breaks.
Unit ConverterConvert length, weight, volume, area, speed, and temperature.
Tip CalculatorWork out the tip and split the bill.