Right Triangle Calculator

About this calculator

This calculator finds the hypotenuse (via the Pythagorean theorem, a² + b² = c²), area (half the product of the two legs, since they meet at a right angle) and perimeter of a right triangle from the lengths of its two legs. A right triangle is any triangle with one 90-degree angle, and the two shorter sides that form that angle are all that's needed to determine everything else about it.

It's used in construction and carpentry to check that a corner is truly square (using the classic 3-4-5 right triangle relationship) and to calculate the length of a diagonal brace, rafter or staircase stringer, and in surveying and navigation to find a direct distance between two points when only the horizontal and vertical distances are known. Students use it constantly as the entry point into trigonometry.