Below is a Pythagorean theorem calculator that solves for any side of a right triangle. Enter two sides and the tool calculates the third.
Pythagorean Theorem Calculator
Using the Pythagorean theorem calculator
Enter any two of the three sides in the Side a (leg), Side b (leg), or Side c (hypotenuse) fields. Leave the third field empty and the calculator solves for the missing side in real-time.
The calculator displays:
- The calculated side highlighted in blue
- The formula used to compute it
- All three side lengths for reference
If you enter all three sides, the calculator verifies whether they form a valid right triangle.
What is the Pythagorean theorem?
The Pythagorean theorem states that in a right triangle, the square of the hypotenuse (the side opposite the right angle) equals the sum of the squares of the other two sides:
Where a and b are the two legs (shorter sides) and c is the hypotenuse (longest side, opposite the right angle).
Example calculation
The classic 3-4-5 right triangle demonstrates the theorem perfectly:
Other common Pythagorean triples (right triangles with whole number sides) include 5-12-13, 8-15-17, and 7-24-25.
