Pythagorean theorem calculator
Find a missing side of a right triangle.
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The formula a² + b² = c² applies only to right triangles. Every side must be positive. In missing-leg mode, the hypotenuse must be longer than the known leg. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Pythagorean theorem calculator
- Enter the values you want to calculate and choose the relevant units or settings.
- The result updates as you type. Adjust the available settings if needed.
- Review the result, then use Copy result or a download link when available.
Useful next steps
How to use it
Choose Hypotenuse and enter both legs, or choose Missing leg and enter one leg followed by the hypotenuse. Use the same measurement unit for both inputs.
A worked example
Legs of 3 and 4 give a hypotenuse of 5. If the hypotenuse is 13 and one leg is 5, the other leg is 12.
What to know
The formula a² + b² = c² applies only to right triangles. Every side must be positive. In missing-leg mode, the hypotenuse must be longer than the known leg.