Triangle Area Calculator

Solve the area of a triangle using the base and height or three sides with the triangle area calculator.

Solve Using:


Area T =  

How to Calculate the Angle of a Triangle

The area of a triangle can be solved using a few formulas, depending on which parts of the triangle are known. The most common ways are using the base length and height or altitude of the triangle, or using Heron’s formula if the sides are known.

Solve Triangle Area given Base and Height

diagram of a triangle showing base b and height h

If the base and height are known then the area of a triangle can be found using the following formula:

T = 12bh

The triangle area T is equal to 1/2 times base b times height h.

Solve Triangle Area given Three Sides

diagram of a triangle showing the sides a, b, & c

If all three sides of the triangle are known then Heron’s formula can be used to solve the triangle’s area

To use Heron’s formula the first step is to find the semiperimeter of the triangle.

s = a + b + c2

The semiperimeter s is equal to side a plus side b plus side c, divided by 2. Thus, the semiperimeter is also equal to half the perimeter.

Once the semiperimeter is solved, substitute it for s in the triangle area formula.

T = s(s – a)(s – b)(s – c)

Heron’s formula states that the area of a triangle T is equal to the square root of the semiperimeter s times s minus side a times s minus side b times s minus side c.

You might also be interested in our area calculator to solve the area of other shapes.