Pythagorean Theorem Calculator

Find any side of a right triangle. Enter the two known sides to calculate the missing one using a² + b² = c². Also calculates triangle area, perimeter, and all angles.

Right Triangle Calculator

Leave the side you want to find empty. Enter the other two.

Pythagorean Theorem

a² + b² = c² Find c (hypotenuse): c = √(a² + b²) Find a (leg): a = √(c² − b²) Find b (leg): b = √(c² − a²) Area = (a × b) / 2 Angle A = arctan(a / b) Angle B = arctan(b / a) [= 90° − A]

Common Pythagorean Triples

abc
345
51213
81517
72425
94041

Frequently Asked Questions

What is the hypotenuse?+
The hypotenuse is the longest side of a right triangle, always opposite the 90° right angle. In the formula a² + b² = c², c is the hypotenuse. It is always longer than either leg (a or b).
Can the Pythagorean theorem work with non-right triangles?+
No — the theorem only applies to right triangles. For other triangles, use the Law of Cosines: c² = a² + b² − 2ab·cos(C), which generalizes the Pythagorean theorem for any angle.

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About the Pythagorean Theorem Calculator

This free pythagorean theorem calculator helps you get accurate results instantly without needing to work through the math manually. Whether you need a quick estimate or a precise figure, having a reliable tool on hand saves time and reduces errors compared to manual calculation.

How to Use This Calculator

  1. Enter your values in the input fields above. Each field is labeled to guide you.
  2. Double-check your inputs — results are only as accurate as the numbers you enter.
  3. Click the Calculate button to see your result instantly.
  4. Use the result for your planning, budgeting, or decision-making.

Why Accurate Calculations Matter

Small errors in math calculations can compound into significant problems. A 1% miscalculation in a budget or measurement can translate to hundreds or thousands of dollars in wasted resources, or result in having to redo work entirely. This calculator uses the standard formulas and methods to give you reliable results you can trust.

Tips for Getting the Best Results

Frequently Asked Questions

Is this calculator free? Yes — completely free with no account, login, or payment required. Use it as many times as you need.

How accurate are the results? This calculator uses the standard formulas for pythagorean theorem calculations. Results are accurate for typical use cases. For specialized or high-stakes applications, consult a professional.

Does it work on mobile? Yes. This calculator is fully responsive and works on smartphones, tablets, and desktops.