Pythagorean Theorem Calculator
Enter any two sides of a right triangle and the third solves live, with a labeled diagram that redraws itself and the steps shown.
Runs entirely on your device - nothing is ever uploaded.
More tools
- Half-Life Calculator Remaining amount after any elapsed time. Get started
- Surface Area Calculator Eight solids with diagrams and steps. Get started
- Percent Error Calculator Experimental vs accepted, with steps. Get started
- Volume Calculator Eight solids with diagrams and steps. Get started
- Abacus Interactive ten-rod soroban with live readout. Get started
- Radians to Degrees Converter Degrees, radians and turns, both ways. Get started
- Standard Deviation Calculator Population and sample SD, with every step shown. Get started
- Fractions Calculator Exact + − × ÷ with mixed numbers. Get started
How to use the Pythagorean calculator
- Enter any two sides: legs a and b, or one leg plus the hypotenuse c.
- The missing side solves instantly and the diagram redraws with your values.
- Enter all three sides to test whether they form a right triangle.
The theorem
In a right triangle, a² + b² = c². The classic 3-4-5 triangle is the simplest integer example: 9 + 16 = 25.
Triples worth memorizing
Integer right triangles cluster around a few triples: 3-4-5, 5-12-13, 8-15-17, and 7-24-25, each with clean multiples like 6-8-10 and 9-12-15. Carpenters use the 3-4-5 rule to square corners: mark 3 units on one wall, 4 on the other, and adjust until the diagonal reads exactly 5. If your sides match no triple, the calculator still tests them - any trio satisfying a² + b² = c² is right-angled, triple or not.