Pythagorean Theorem Calculator
Calculate the hypotenuse of a right triangle from its two legs, using the Pythagorean theorem (a² + b² = c²).
- Free to use
- Accurate results
- No registration required
- Works on all devices
Enter the two legs of a right triangle to calculate the hypotenuse using a² + b² = c².
Your result
5
Hypotenuse (c)
Perimeter12
AI explanation
Formula
c = √(a² + b²)Worked example
Classic 3-4-5 right triangle
| Field | Value |
|---|---|
| First leg (a) | 3 |
| Second leg (b) | 4 |
| Hypotenuse (c) | 5 |
| Perimeter | 12 |
Assumptions
- Applies only to right triangles, where the two legs meet at a 90° angle.
- For the full triangle solution including angles and area, use the Right Triangle Calculator.
Frequently asked questions
What is the Pythagorean theorem?
For any right triangle, the square of the hypotenuse (the side opposite the right angle) equals the sum of the squares of the other two sides: a² + b² = c².
What are some other well-known Pythagorean triples?
Besides 3-4-5, common whole-number examples include 5-12-13, 8-15-17, and 7-24-25 — sets of three whole numbers that satisfy a² + b² = c² exactly.
How do I find the area and angles too?
Use the Right Triangle Calculator, which computes the hypotenuse along with area, perimeter, and both acute angles from the same two legs.