Right triangle calculator
Enter any two sides of a right triangle. The calculator finds the third side, both acute angles, area and perimeter.
How do I use this page?
- Enter any two side lengths.
- Leave the third field empty.
- Read the sides, angles, area and perimeter with substituted formulas.
What this page does not do: Enter at least two positive side lengths. If all three are entered, they must form a right triangle.
Further reading
Formula
a² + b² = c²; A = ab/2 Theory — what is the Pythagorean theorem?
The Pythagorean theorem relates the sides of a right triangle: the sum of the squares of the two legs equals the square of the hypotenuse. Given any two sides, the calculator finds the third side, both acute angles, the area and the perimeter of the triangle. For example, with legs of 3 and 4, the hypotenuse is 5, the area is 6, and the perimeter is 12. This relationship applies only to right triangles.
Frequently asked questions
How do I find the hypotenuse?
How do I find a missing leg?
Does the calculator find angles?
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