EN

mathClassic tool

Pythagorean Theorem Calculator

Find a missing leg or hypotenuse, plus triangle area and perimeter, from any two sides of a right triangle.

Use this Pythagorean theorem calculator to find the missing side of a right triangle without doing the equation by hand. Enter any two sides, leave the unknown side blank, and the tool returns the missing value together with the triangle perimeter and area.

How to use it

  • Fill in exactly two fields.
  • Use c for the hypotenuse, which must be the longest side.
  • Leave blank the side you want to solve.

The base equation is a² + b² = c². If the hypotenuse is missing, the calculator adds the squares of both legs. If a leg is missing, it subtracts the square of the known leg from the square of the hypotenuse.

This page is useful for homework, classroom review, construction checks, layout measurements, geometry practice and quick answer verification.

Leave only one side blank. Tool solves the right triangle with the Pythagorean theorem.

Tip: if you enter the hypotenuse, it must be larger than both legs.

SummaryFill in two sides and leave one blank to calculate it.
Solved side—
Found value—
Perimeter—
Area—
Applied formulaa² + b² = c²
Short stepsCalculation summary will appear here.

Use clear inputs to get a more useful result.