Math calculator

Pythagorean Theorem Calculator

Choose the missing side and enter the two known right-triangle lengths.

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No account. Formula and assumptions are shown below.

Calculator inputs

Pythagorean theorem details

Formula & disclaimer

Hypotenuse² = Leg A² + Leg B²

View assumptions

Formula reviewCalcs at Hand Editorial TeamVerified 31 August 2026 · automated checks included

Three useful checks, kept deliberately short.

What this result includes

The hypotenuse is 5 units.

A practical example

Find the hypotenuse of a 3 by 4 right triangle: Square both legs · Add the squared values · Take the square root.

Common input mistake

When solving for a leg, enter the hypotenuse as Known length A and the known leg as Known length B.

Hypotenuse² = Leg A² + Leg B²

The relationship applies only to right triangles.

Keep in mind: Confirm that the triangle is right-angled before applying this theorem.

Produced byCalcs at Hand Editorial Team

Last formula check31 August 2026

Review methodKnown examples + boundary cases