triangle area calculator

Select Calculation Method:

Base (units):

Height (units):

Side A (units):

Side B (units):

Side C (units):

How to Calculate the Area of a Triangle

Calculating the area of a triangle depends on the information you have available. The most common method requires knowing the base and the height, but if you only know the lengths of the three sides, you can use Heron's Formula.

Method 1: Base and Height

This is the simplest method. The area is equal to half the product of the base and the height.

Formula: Area = 0.5 × base × height

For example, if a triangle has a base of 10 units and a height of 5 units, the area is 0.5 × 10 × 5 = 25 square units.

Method 2: Heron's Formula (Three Sides)

If you do not know the height, you can calculate the area using the lengths of all three sides. First, calculate the semi-perimeter (s), which is half the perimeter of the triangle.

Step 1: s = (a + b + c) / 2

Step 2: Area = √(s(s-a)(s-b)(s-c))

This formula is particularly useful for irregular triangles where the height is difficult to measure directly.