Heron's Formula Calculator

Calculate the area of any triangle using only its three side lengths with Heron's Formula.

Triangle Area:

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Understanding Heron's Formula

a b c

The Formula

Heron's Formula states that the area (A) of a triangle with sides a, b, and c is:

A = √(s(s-a)(s-b)(s-c))

where s is the semi-perimeter: s = (a + b + c)/2

When to Use It

  • When you only know the three side lengths of a triangle
  • When calculating the area without knowing the angles
  • For irregular triangles where height is difficult to measure

Triangle Inequality Theorem

Remember: For a triangle to exist, the sum of any two sides must be greater than the third side.