Everyday numbers, worked out in seconds.

Loan payments, discounts, BMI, your exact age, GPA and more. Type your numbers and the answer updates as you go. Each calculator comes with a plain-English guide to the math behind it.

  • Free, no sign-up
  • Works on any phone
  • Your numbers stay on your device

Try it: what is X% of Y?

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How our calculators work

The formula is always shown

Every calculator has a guide with the exact formula, a worked example you can check by hand, and the limits of the result. If you can't see how a number was made, you shouldn't have to trust it.

Nothing leaves your device

The math runs in your browser. We don't save, send or see the numbers you enter, so you can use real figures for a loan or your health.

Standard, cited methods

We use the formulas lenders, doctors and schools use: the standard amortization formula for loans, WHO categories for BMI, and the Mifflin-St Jeor equation for calories.