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Quick answer: enter any two sides above — the calculator finds the third using a² + b² = c², e.g. sides 3 and 4 give hypotenuse 5.
Pythagorean theorem calculator
Short answer: the Pythagorean theorem states a² + b² = c² for right triangles. Enter two sides above and solve for the hypotenuse or either leg.
Pythagorean theorem formula
Short answer: the Pythagorean theorem formula is a² + b² = c². Hypotenuse: c = √(a² + b²). Leg: a = √(c² − b²). The calculator applies the right form automatically.
Frequently asked questions
What is the Pythagorean theorem?
In a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c².
How do you find the hypotenuse?
c = √(a² + b²). For sides 3 and 4: √(9 + 16) = √25 = 5. Select "Find hypotenuse" above and enter the two legs.
How do you find a missing leg?
a = √(c² − b²). Select "Find side a", enter the other leg and the hypotenuse — the calculator handles it.
What is a 3-4-5 triangle?
The most famous Pythagorean triple: 3² + 4² = 5² (9 + 16 = 25). Other triples include 5-12-13 and 8-15-17.
Does it work for non-right triangles?
No — the theorem only applies to right triangles (one 90° angle). For other triangles, use the law of cosines.
Is this Pythagorean calculator free?
Yes — unlimited calculations, free forever. No account, no limits. Everything runs in your browser.