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Triangle Area Calculator (Heron)

Triangle area from three side lengths using Heron's formula.

Find the area of any triangle from the lengths of its three sides using Heron's formula — no angles required.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Half-perimeter s = (a + b + c) / 2. Then Area = √(s(s−a)(s−b)(s−c)).

In depth

Find the area of any triangle from the lengths of its three sides using Heron's formula — no angles required.