Triangle Calculator

A triangle calculator finds a triangle's area, perimeter and type (equilateral, isosceles or scalene) directly from its three side lengths — no angles required. This kind of calculation underlies land surveying, construction and structural engineering, anywhere a triangular shape's dimensions need to be verified or worked out from measured sides.

Enter the three side lengths. The calculator first checks they satisfy the triangle inequality (any two sides must add up to more than the third, or no such triangle can exist), then finds the area using Heron's formula — computing the semi-perimeter s (half the perimeter) and taking the square root of s(s−a)(s−b)(s−c) — while comparing the side lengths to classify the triangle's type.

Area = √(s(s−a)(s−b)(s−c)), where s = (a+b+c)/2