c = 5
Pythagorean Theorem Calculator
Use this free Pythagorean theorem calculator to solve for the hypotenuse or a missing leg of a right triangle with steps and examples.
Formula steps Examples included Copy results Private history
Hypotenuse c5 cm
- Leg a
- 3 cm
- Leg b
- 4 cm
- Hypotenuse c
- 5 cm
Steps
- Use the Pythagorean theorem for right triangles: a^2 + b^2 = c^2.
- Solve c by taking sqrt(a^2 + b^2).
- The missing side is 5 cm.
How to use the pythagorean theorem calculator
- Choose whether you need the hypotenuse, leg a, or leg b.
- Enter the two known side lengths of the right triangle.
- Press Calculate side to solve the missing side with a^2 + b^2 = c^2.
- Use examples, recent answers, or copy the result while checking right-triangle work.
Common uses
Find the hypotenuse when both legs are known.
Find a missing leg when one leg and the hypotenuse are known.
Check right triangle side lengths for homework.
Copy formula steps for Pythagorean theorem practice.
Examples
a = 5
b = 15
Frequently asked questions
Quick answers about formulas, units, valid measurements, examples, copying, and private in-browser history.
What formula does the calculator use?
It uses the Pythagorean theorem: a^2 + b^2 = c^2, where c is the hypotenuse of a right triangle.
Can it solve for a missing leg?
Yes. If you know the hypotenuse and one leg, it subtracts the known leg squared from the hypotenuse squared, then takes the square root.
Does the Pythagorean theorem work for every triangle?
No. It only applies to right triangles with one 90-degree angle.
What if the hypotenuse is shorter than a leg?
That input is invalid for a right triangle. The hypotenuse must be the longest side.
Should I use the Right Triangle Calculator instead?
Use this tool when you only need a missing side. Use the Right Triangle Calculator when you also want area, perimeter, and angles.
Is my Pythagorean history private?
Yes. Recent Pythagorean answers stay only in the current browser tab while you use the page. They are not sent to a server.