This right triangle calculator calculates the sides, dimensions and angles, perimeter and area of a right triangle by using the Pythagorean theorem & Heron’s formula.

Side a:
Side b:
Side c:
Angle A:
Angle B:

How does this right triangle calculator work?

This tool is designed to find the sides, angles, area and perimeter of any right triangle if you input any 3 fields (any 3 combination between sides and angles) of the 5 sides and angles available in the form.

The algorithm of this right triangle calculator uses the Pythagorean theorem to calculate the hypotenuse or one of the other two sides, as well as the Heron formula to find the area, and the standard triangle perimeter formula as described below. Moreover it allows specifying angles either in grades or radians for a more flexibility.

Pythagorean theorem

Also known as Pythagoras's theorem this states that in a right trianglethe square of the hypotenuse “c”  (the side opposite the right angle) equals the sum of the squares of the other two sides “a” & “b”, thus its equation can be written as presented here:

a2 + b2 = c2

Then in order to find:

-the hypotenuse the equation becomes c = square root (a2 + b2)

- the side a formula is a = square root (c2 - b2)

- the side b expression is b = square root (c2 - a2)

Heron formula for area of a triangle

Area = square root (s(s - a)(s - b)(s - c))


s = semi perimeter of the triangle having this formula s = (a + b + c) / 2

Triangle perimeter formula

Perimeter = a + b + c

Where: a,b and c are the sides of the triangle.

11 Apr, 2015