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Geometry

Triangle Area from Three Sides Calculator

Calculate triangle area when all three side lengths are known.

Use consistent dimensionsArea and volume units explained below

Shape dimensions

Runs on your device

GEOMETRIC RESULT

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter side a, side b, side c.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

s = (a + b + c)/2. Area = √[s(s − a)(s − b)(s − c)].

A WORKED EXAMPLE

Using side a = 3 m, side b = 4 m, side c = 5 m, the result is 6 m². Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Use the indicated units consistently. Ideal shapes are assumed; dimensions must describe the same object. Display rounding does not increase measurement precision.

Common questions

Which inputs does this calculation need?

Calculate triangle area when all three side lengths are known. Enter side a in m, side b in m, side c in m. The filled example is editable and is not a saved personal record.

How should I interpret the result?

Use the indicated units consistently. Ideal shapes are assumed; dimensions must describe the same object. Display rounding does not increase measurement precision.

Methodology maintained by ClarityKit. How these tools are built and checked.