Online Tool Store
Pythagorean Theorem Calculator
Solve for a right triangle's hypotenuse or either leg using the Pythagorean theorem, with input validation and the formula shown. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Example shown - a 3-4-5 right triangle.
Result
How the Pythagorean theorem calculator works
- Choose which side you want to solve for - a leg or the hypotenuse.
- Enter the two known side lengths.
- The missing side is calculated instantly using the Pythagorean theorem.
The formula
a² + b² = c²
Example: a right triangle with legs 3 and 4 has a hypotenuse of √(3² + 4²) = √25 = 5 - the classic "3-4-5 triangle" shown by default above.
FAQ
Does this only work for right triangles?
Yes. The Pythagorean theorem specifically relates the two legs and hypotenuse of a right triangle - it does not apply to triangles without a 90° angle.
Which side is the hypotenuse?
The hypotenuse is always the longest side, opposite the right angle. The tool enforces that the hypotenuse must be larger than either leg when solving for a leg.
Can I solve for a missing leg instead of the hypotenuse?
Yes. Use the "Solve for" dropdown to choose leg a, leg b, or the hypotenuse c, and enter the two known values.
What real-world problems use this?
Finding a diagonal distance (screen sizes, ladder placement against a wall), navigation shortcuts, and construction measurements are common practical uses.
How we compare
| Feature | Online Tool Store | Calculator.net | Manual calculation |
|---|---|---|---|
| Solves for any of the three sides | ✓ | ✓ | Depends on you |
| Validates hypotenuse vs. leg length | ✓ | ✗ | ✗ |
| No ads | ✓ | ✗ | ✓ |
For a quick, error-checked right-triangle solve, Pythagorean Theorem Calculator saves the manual arithmetic.