Pythagorean Theorem Calculator
Enter any two sides of a right triangle and leave the unknown side blank. Uses a² + b² = c².
Using the Pythagorean theorem
The theorem relates the three sides of a right triangle: a² + b² = c², where c is the hypotenuse (the side opposite the right angle). Given any two sides, you can solve for the third. This is widely used in construction, navigation, and geometry.
Popular right triangles
legs 3 & 4 · legs 5 & 12 · legs 6 & 8 · legs 9 & 12 · legs 8 & 10 · legs 1 & 1 · legs 2 & 3 · legs 5 & 5 · legs 10 & 10 · legs 7 & 9
Frequently asked questions
What is the Pythagorean theorem?
For a right triangle, the square of the hypotenuse (c) equals the sum of the squares of the two legs: a² + b² = c². It only applies to right-angled triangles.
How do I find the hypotenuse?
Enter the two legs (a and b) and leave c blank. The calculator returns c = √(a² + b²).
How do I find a missing leg?
Enter one leg and the hypotenuse, and leave the other leg blank. The calculator returns √(c² − leg²). The hypotenuse must be the longest side.