Pythagorean Theorem Calculator

Free Pythagorean Theorem Calculator — find the hypotenuse or any leg of a right triangle using a² + b² = c², or verify whether three sides form a right triangle.

869.0K usesUpdated · 2026-04-28Runs locally · zero upload

How to Use Pythagorean Theorem Calculator

The Pythagorean Theorem Calculator solves for any missing side of a right triangle in seconds.

  1. Choose a calculation mode — select "Find Hypotenuse (c)", "Find Leg (a)", "Find Leg (b)", or "Verify Right Triangle" in the Pythagorean Theorem Calculator.
  2. Enter the known sides — input the two values you have. All inputs must be positive numbers.
  3. Read the result — the Pythagorean Theorem Calculator displays the missing side and the full calculation step so you can follow the working.

The Pythagorean Theorem Calculator also includes a verification mode: enter all three sides and it tells you immediately whether they satisfy a² + b² = c².

Formula & Theory — Pythagorean Theorem Calculator

The Pythagorean Theorem Calculator is built on the most fundamental relationship in Euclidean geometry:

a² + b² = c²

Derived formulas used by the Pythagorean Theorem Calculator:

Find hypotenuse:  c = √(a² + b²)
Find leg a:       a = √(c² − b²)
Find leg b:       b = √(c² − a²)
Symbol Meaning
a, b The two legs (sides adjacent to the right angle)
c The hypotenuse (side opposite the right angle)

The theorem was known to Babylonian mathematicians around 2000 BCE and is attributed to the ancient Greek mathematician Pythagoras (~570–495 BCE). The Pythagorean Theorem Calculator applies these formulas with floating-point precision and shows the computation step so students can verify their own work.

Validity constraints

The Pythagorean Theorem Calculator enforces two rules: all inputs must be positive, and the hypotenuse (c) must be strictly greater than either leg. If these conditions are violated, an error is displayed.

Use Cases for Pythagorean Theorem Calculator

The Pythagorean Theorem Calculator is widely used in:

  • Mathematics education — students use the Pythagorean Theorem Calculator to check answers for right-triangle problems in class or homework.
  • Construction and carpentry — verify that a corner is square by entering the two wall lengths and the diagonal; the Pythagorean Theorem Calculator confirms the expected hypotenuse.
  • Navigation and surveying — compute straight-line distances from horizontal and vertical measurements using the Pythagorean Theorem Calculator.
  • Engineering — find cable run lengths, ramp dimensions, or ladder reach with the Pythagorean Theorem Calculator.
  • Game development — calculate 2D Euclidean distances between points by treating coordinate differences as legs in the Pythagorean Theorem Calculator.

Whether you are solving a textbook problem or designing a physical structure, the Pythagorean Theorem Calculator delivers accurate, step-by-step results in your browser.

Frequently asked questions about Pythagorean Theorem Calculator

How does the Pythagorean Theorem Calculator work?

Enter any two sides of a right triangle and the Pythagorean Theorem Calculator instantly applies a² + b² = c² to find the missing side. You can also use it to verify whether three given sides satisfy the theorem.

Can the Pythagorean Theorem Calculator find a leg instead of the hypotenuse?

Yes. Switch the mode to 'Find Leg (a)' or 'Find Leg (b)' in the Pythagorean Theorem Calculator and provide the other leg and the hypotenuse.

What happens if I enter a hypotenuse smaller than a leg?

The Pythagorean Theorem Calculator detects this invalid input and shows an error, since the hypotenuse must always be the longest side of a right triangle.

Is my data stored?

No. All calculations happen in your browser; nothing is sent to a server.