How do you find the area of a triangle?

The simplest formula is A = ½ × base × height. The height must be perpendicular to the base.

What if I do not know the height?

If you know all three sides, use Heron's formula: A = √(s(s-a)(s-b)(s-c)), where s = (a+b+c)/2. If you know two sides and the included angle, use A = ½ × a × b × sin(C).

Free Triangle Area Calculator

Calculate the area of a triangle using base and height. The most common and straightforward triangle area formula.

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Base

Height

Area

30.0000

Perimeter Note60.0000

View formula & how it works →

How to Calculate Triangle Area

Formula

A = ½ × base × height

Where:

base = the length of one side of the triangle

height = the perpendicular distance from the base to the opposite vertex

This formula works for all triangles — the height must be perpendicular to the base.

Example Calculation

Find the area of a triangle with base 10 and height 6.

01A = ½ × 10 × 6
02= ½ × 60
03= 30

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