Heron Formula Calculator
You do not need the height of a triangle to find its area. Enter the three side lengths and this calculator applies Heron's formula — finding the semi-perimeter first, then the area — with every step shown so you can follow the working.
How to use
- Enter the lengths of all three sides of the triangle.
- The calculator first finds the semi-perimeter s = (a + b + c) ÷ 2.
- Then it applies Heron's formula — area = √(s(s−a)(s−b)(s−c)) — with the steps shown.
Good to know
- Heron's formula works for any triangle — no height or angle is needed.
- The three sides must pass the triangle rule: the sum of any two sides must exceed the third.
- The semi-perimeter s is simply half of the triangle's perimeter.
Note: The three sides must pass the triangle inequality: the sum of any two sides must be greater than the third. Otherwise no such triangle exists.