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Pythagorean Theorem Calculator

Leave exactly one field blank to calculate its value. Uses: A² + B² = C²
Side A
Side B
Hypotenuse C
Pythagorean Triple
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Enter values to see the worked formula.

What Your Result Means

How This Calculator Works

The Pythagorean theorem states that in a right triangle, A² + B² = C², where C is the hypotenuse. This calculator uses that formula to find the missing side when you provide any two sides. Enter exactly two sides and leave one blank, and the calculator solves for the unknown using algebra.

Quick Questions

What's a Pythagorean triple?

A set of three whole numbers that satisfy A² + B² = C². Examples: 3-4-5, 5-12-13, and 8-15-17.

What if my triangle doesn't have a 90-degree angle?

This calculator only works for right triangles (with one 90° angle). For other triangles, use the Law of Cosines.

Why do I get decimal results?

Most combinations of side lengths don't produce whole numbers. Decimals are accurate; only integer results form Pythagorean triples.

Sources

Method & review

MethodologyHow we calculate this Reviewed & Updated2026-04 Next review2027-04

Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.