Pythagorean Theorem Calculator
Find the hypotenuse of a right triangle from its two legs.
Formula: c = √(a² + b²)
Worth Knowing
This only holds for right triangles — the 90° angle is what makes the relationship work, since the theorem is really a statement about the areas of squares built on each side. It shows up constantly outside of math class too: finding the diagonal of a rectangular screen or room, calculating the shortest straight-line distance between two points on a grid, or checking whether a corner is truly square on a job site (the classic 3-4-5 triangle trick is just this formula with a=3, b=4, giving a hypotenuse of exactly 5).
How to Use
- Enter Leg a into the first field of the Pythagorean Theorem Calculator.
- Fill in the rest: Leg b.
- Your result appears instantly as you type — there's no submit button or page reload.
Formula
c = √(a² + b²)