Pythagorean Theorem Calculator

The Pythagorean theorem calculator finds any side of a right triangle: the Hypotenuse, Leg A or Leg B. The legs are the two sides that meet at the right angle, and the hypotenuse is the longest side, opposite the right angle. Enter any two sides and the missing one is calculated automatically.

How it works

In a right triangle, the square of the hypotenuse equals the sum of the squares of the legs:

\[ Hypotenuse^2 = Leg_A^2 + Leg_B^2 \]

To find a leg, subtract the square of the other leg from the square of the hypotenuse and take the square root. The hypotenuse must always be longer than each leg; otherwise the triangle does not exist.

Example

A right triangle has legs of 3 and 4. The hypotenuse is √(3² + 4²) = √25 = 5. If you know the hypotenuse is 5 and one leg is 4, leave the other leg empty and the calculator finds 3.