Pythagorean Theorem Calculator
Solve for any missing side of a right triangle.
Enter your values
Enter the leg a you are working with.
Enter the leg b you are working with.
Enter the hypotenuse c (leave blank to solve) you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Hypotenuse c
- 5
- Leg a
- 3
- Leg b
- 4
- Area
- 6
- Angles
- 36.87° and 53.13°
Working
- 1c = √(3² + 4²) = 5
Quick answer
In a right triangle a² + b² = c², where c is the hypotenuse opposite the right angle.
a² + b² = c²
At a glance
| What it does | Solve for any missing side of a right triangle. |
|---|---|
| Category | Math |
| Inputs needed | Leg a, Leg b, Hypotenuse c (leave blank to solve) |
| Formula | a² + b² = c² |
| Cost | Free — no sign-up, no download |
How to use the Pythagorean Theorem Calculator
- 1Enter any two sides.
- 2Leave the unknown side blank.
- 3Read the missing side, area and angles.
Inputs explained
- Leg a
- Enter the leg a you are working with.
- Leg b
- Enter the leg b you are working with.
- Hypotenuse c (leave blank to solve)
- Enter the hypotenuse c (leave blank to solve) you are working with.
Frequently asked questions
What is a Pythagorean triple?
Three whole numbers satisfying a² + b² = c², like 3-4-5, 5-12-13 and 8-15-17.
Does it work on non-right triangles?
No. Use the law of cosines, which reduces to Pythagoras when the angle is exactly 90°.
What do I need to enter into the Pythagorean Theorem Calculator?
Just 3 values: leg a, leg b, hypotenuse c (leave blank to solve). Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Pythagorean Theorem Calculator work out the answer?
In a right triangle a² + b² = c², where c is the hypotenuse opposite the right angle. It applies the formula a² + b² = c² and shows the working so you can check each step by hand.
Is the Pythagorean Theorem Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.