In a right triangle, the square of the hypotenuse equals the sum of the squares of the legs: c² = a² + b². Attributed to Greek mathematician Pythagoras (~570–495 BC).
Pythagorean Theorem Calculator
Enter two sides of a right triangle and calculate the third using a²+b²=c².
Pythagorean theorem with symbolic solution and step-by-step check.
The Pythagorean theorem states that in any right triangle, the square of the hypotenuse (side opposite the right angle) equals the sum of the squares of the legs: a²+b²=c². This tool accepts any two sides and calculates the third, showing the equation with values substituted.
Fill in two fields to calculate the third.
- Enter values for any two sides (legs a, b or hypotenuse c).
- The third side is calculated automatically.
- See the complete equation and step-by-step solution.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
- Pythagorean Theorem — Wolfram MathWorldWolfram MathWorld — Statement, proofs and applications of the Pythagorean theorem.
- Pythagorean Theorem — WikipediaWikipedia — History, proofs and generalizations of the Pythagorean theorem.
- Pythagorean Theorem — Khan AcademyKhan Academy — Review with practical examples of theorem application.