Pythagorean Theorem Calculator
Find the missing side of a right triangle using a² + b² = c². Enter any two sides — the calculator figures out which one is the hypotenuse and solves.
Inputs
Leave 0 if you want to compute it. Otherwise the calculator finds the missing leg.
Side c (hypotenuse)
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Side a
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Side b
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Angle opposite a
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Angle opposite b
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Area
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Perimeter
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About Pythagorean Theorem Calculator
The theorem
For a right triangle (one 90° angle), the squares of the two shorter sides (legs a and b) sum to the square of the longest side (hypotenuse c). Written: a² + b² = c².
Famous triples
Whole-number solutions: 3-4-5, 5-12-13, 8-15-17, 7-24-25, 9-40-41. Any multiple works too — 6-8-10 is just 3-4-5 doubled. Useful in construction for verifying square corners.
Origin
Known and used by Babylonian and Egyptian builders centuries before Pythagoras (c. 500 BCE) proved it formally. The Babylonian Plimpton 322 tablet (c. 1800 BCE) lists Pythagorean triples.