Heron's formula calculator
Find the area of any triangle from its three side lengths using Heron's formula.
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Tool guide
Heron's formula calculator: how it works
Practical information to understand the result and use this tool correctly.
About Heron's formula calculator
Heron's formula finds area from three side lengths alone using the semi-perimeter s.
It works for any non-degenerate triangle: scalene, isosceles, or equilateral.
The tool also shows s and the perimeter so you can verify the triangle inequality.
How to use it
- 1Enter sides a, b, and c in the same unit.
- 2Calculate area and semi-perimeter.
- 3If the sides cannot form a triangle, fix the lengths.
Frequently asked questions
- Need the height?
- No — that is the point of Heron's formula.
- Triangle inequality?
- Each side must be shorter than the sum of the other two.