Pythagoras Calculator
Find the missing side of a right triangle: the hypotenuse or either leg.
Quick answer: enter your details below and click Calculate — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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Calculators
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How to use
- Choose which side you want to find.
- Enter the two sides you already know.
- Calculate to see the missing side.
About this tool
Choose which side is missing and enter the two sides you know. To find the hypotenuse, the tool takes the square root of the sum of the squares of the legs. To find a leg, it takes the square root of the hypotenuse squared minus the other leg squared, and it warns you if the hypotenuse is not longer than the known leg, since that cannot happen in a real triangle.
Frequently asked questions
Can the hypotenuse be shorter than a leg?
No. The hypotenuse is always the longest side of a right triangle, so if your numbers say otherwise, one of them must be wrong.
Does this work for triangles that are not right-angled?
No. Pythagoras only applies when one angle is exactly 90 degrees.