Triangle Area Calculator
Find the area of a triangle from its base and height, or from the lengths of its three sides.
Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026
Area
30
area = ½ × 10 × 6 = 30
How do you find the area of a triangle?
The most common way is half the base times the height: area = ½ × base × height, where the height is the perpendicular distance from the base to the opposite corner. If you don't know the height but know all three side lengths, you can use Heron's formula instead.
Heron's formula
Heron's formula finds the area from the three sides alone. First compute the semi-perimeter s = (a + b + c) ÷ 2, then the area is √(s(s − a)(s − b)(s − c)). It works for any triangle as long as the three lengths can actually form one.
Example
A triangle with a base of 10 and a height of 6 has an area of ½ × 10 × 6 = 30. Using Heron's formula, a 3-4-5 triangle has s = 6, so the area is √(6 × 3 × 2 × 1) = √36 = 6.
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Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer
How to use
Choose a mode, then enter the measurements. The calculator updates instantly.
Base and height: area = ½ × base × height. Three sides: uses Heron's formula with the semi-perimeter.