How it works
For a right triangle, the square of the hypotenuse equals the sum of the squares of the two perpendicular legs. Both legs must be positive for a triangle with area.
Standard formula
c = √(a² + b²)Worked example
For legs 3 and 4, c = √(3² + 4²) = 5.
Frequently Asked Questions
Which side is the hypotenuse?
It is the side opposite the right angle and the longest side of a right triangle.
Can I find a missing leg?
This version calculates the hypotenuse from both legs. Rearrange the formula to find a leg when needed.
Does the unit matter?
Both inputs must use the same unit; the answer uses that same unit.
Does it work for any triangle?
No. The Pythagorean theorem applies to right triangles.