Hypotenuse calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- c = √(a² + b²) = √(25 + 144) = √169 = 13.
| Inputs | Answer |
|---|---|
| Leg a: 5; Leg b: 12 | The hypotenuse of a right triangle with legs 5 and 12 is 13. |
| Leg a: 3; Leg b: 4 | The hypotenuse of a right triangle with legs 3 and 4 is 5. |
| Leg a: 1; Leg b: 1 | The hypotenuse of a right triangle with legs 1 and 1 is 1.414214. |
How to use it
The hypotenuse is the side opposite the right angle and the longest side of a right triangle. From the legs a and b it is c = √(a² + b²).
The calculator also gives the triangle's area (a × b ÷ 2) and perimeter.
Frequently asked questions
What is the hypotenuse of a triangle with legs 5 and 12?
13, since √(25 + 144) = √169 = 13.
Is the hypotenuse always the longest side?
Yes.
How do I find a leg if I know the hypotenuse?
Use the Pythagorean theorem calculator and choose to find a leg.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
Written by Calculators Free Editorial Team · Data checked 2026-11-12
About · How we verify this · Editorial policy · Corrections
About · How we verify this · Editorial policy · Corrections
General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.