Triangle Area (Heron) Calculator

About this calculator

This calculator finds a triangle's area using only its three side lengths, via Heron's formula, which avoids needing to know an angle or drop a height — useful because a triangle's area is normally taught as half of base times height, information that is not always available from a real-world measurement. It also returns the perimeter as a simple side-length sum.

It is used by students verifying geometry homework, by surveyors, carpenters and DIYers who measured three edges of a triangular plot, panel or piece of land and need the area without a protractor, and by anyone who just knows three side lengths and needs the enclosed area quickly.