Calculators that show
their work
Percentages, unit conversions, mortgage math, BMI. Every result includes the formula so you can check it yourself.
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Tools for money, health, math, and every unit conversion you'll run into.
Calculators
Unit conversions
Why we show the formula
Most calculator sites give you a number and that's it. We think you should see how the answer was calculated, so you can sanity-check it and learn the math for next time.
The percentage calculator handles seven problem types: "what is 15% of 200," "what percent is 30 of 150," percent change, reverse percentages, adding or subtracting a percent, and percent difference. Need to convert inches to centimeters or Fahrenheit to Celsius? Same deal: you see the conversion factor and the math.
Everything runs in your browser. No data leaves your device, no account needed.