What does this tool do?
The Pythagorean calculator finds the missing side of a right triangle using the relationship a² + b² = c². Solve for the hypotenuse from two legs, or solve for a leg when you know the hypotenuse and the other leg, with the result shown instantly as a decimal. It is handy for students, carpenters, and anyone doing construction layout.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
Which side are you solving for?
The tool offers three modes. 'Find c' computes the hypotenuse from the two legs, while 'Find a' and 'Find b' return the missing leg from the hypotenuse and the other leg. When solving for a leg, the hypotenuse you enter must be larger than the known leg, otherwise the triangle is geometrically impossible and the tool warns you. Results update the moment you change a value, so there is no separate calculate button to press.
Where it is useful in real life
The Pythagorean theorem is more than a homework exercise. It is used to check whether a wall is truly square with the 3-4-5 method, to find how high a ladder reaches, to work out a screen diagonal, or to measure the straight-line distance between two points. Because this calculator also accepts decimal side lengths, you can rely on it for precise design and woodworking measurements as well.
Frequently asked questions
How do I solve for a leg instead of the hypotenuse?
Click the 'Find a' or 'Find b' button at the top, then enter the hypotenuse (c) and the known leg. The tool takes the square root of c² minus that leg squared to return the missing side.
Why do I get a 'hypotenuse must be larger than the leg' warning?
In a right triangle the hypotenuse is always the longest side. When solving for a leg, if the hypotenuse you enter is equal to or smaller than the known leg, no valid triangle exists, so the tool stops the calculation.
Can I enter decimal values?
Yes. The fields step in increments of 0.1 and accept any decimal you type. The result is shown to four decimal places with unnecessary trailing zeros trimmed.
Is Pythagorean Calculator free?
Yes. Pythagorean Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Pythagorean Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.