Triangle area from sides Calculator

How to calculate triangle area from sides

This tool calculates triangle area from sides from Side A, Side B, Side C. Enter each quantity in its labelled field, then use the formula below to check the calculation.

Formula

Heron: √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2

Worked example

Side A

3

Side B

4

Side C

5

Applying the formula to these values gives 6 square units.

What should I check?

Find the area, perimeter, surface area or volume of common shapes. Use consistent length units: metres produce square metres for areas and cubic metres for volumes.

Use the reset button to restore this example. Your inputs are processed in this browser and are not included in a shared calculator link. See our methodology and limitations.