UtilityBaseCalculators
Pythagorean Theorem Calculator
Solve any right triangle from two values — get the missing side, both angles, area, and a labeled diagram.
Updated July 10, 2026
How to use the pythagorean theorem calculator
- 1Pick which two values you know.
- 2Enter the two measurements.
- 3Read the missing side, angles, area, and perimeter.
- 4Follow the worked steps and scaled diagram.
Common uses
- Homework on the Pythagorean theorem
- Finding a diagonal or brace length in DIY projects
- Checking a right angle on a layout
- Solving a right triangle from a side and angle
Frequently asked questions
What is the Pythagorean theorem?
In any right triangle, the square of the hypotenuse (the side opposite the right angle) equals the sum of the squares of the other two sides: a² + b² = c². It only holds for right triangles.
How do I find the hypotenuse?
Square both legs, add them, and take the square root: c = √(a² + b²). For legs of 3 and 4, that's √(9 + 16) = √25 = 5. Enter the two legs and the calculator does this and shows the steps.
Can I solve a right triangle from a side and an angle?
Yes. Choose the leg-and-angle or hypotenuse-and-angle mode and the calculator uses trigonometry — sine, cosine, and tangent — to find the remaining sides and the other angle.
About this tool
The Pythagorean theorem calculator finds the missing measurements of a right triangle using a² + b² = c². Enter any two values — two legs, a leg and the hypotenuse, or a side and an angle — and it returns the missing side, both acute angles, the area, and the perimeter, with the worked steps shown and a labeled triangle drawn to scale. It's built for students and anyone who needs the hypotenuse or a leg quickly, like construction and DIY layout. Everything is computed in your browser.
Like most tools on UtilityBase, the pythagorean theorem calculator runs entirely in your browser — nothing you enter is uploaded or stored on a server. It's free to use with no account required. Browse more calculators here.
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