Heron's Formula Calculator

About this calculator

This calculator finds a triangle's area using Heron's formula, Area = √(s(s−a)(s−b)(s−c)), where s is the semi-perimeter (a+b+c)/2 and a, b, c are the three side lengths. Attributed to Heron of Alexandria (1st century AD), its key advantage is that it needs only the three side lengths — no height or angle measurement required — making it the natural choice whenever a triangle's height isn't directly measurable.

Surveyors and land assessors use it to compute the area of irregularly shaped triangular plots measured only by boundary lengths; architects and civil engineers use it for triangular structural sections and site layouts; and geometry students use it as a standard alternative to the base-times-height formula. Enter the three side lengths to get the triangle's area.