Square Feet of a Triangle Calculator
Table of contents
How do I use the square feet of a triangle calculator?How do I calculate the square feet of a triangle?Related calculatorsFAQsWelcome to the square feet of a triangle calculator, where we'll explain all there is to know about how to calculate the square feet of a triangle. Let's get to the point and calculate some triangles' square feet!
How do I use the square feet of a triangle calculator?
Using the square feet of a triangle calculator is easy! Follow these steps:

Select what you know about the triangle from the list. You can find the square feet of triangles if you know the following combination of length and angles:
 Base and height;
 Three sides (SSS);
 Sideangleside (SAS); and
 Anglesideangle (ASA).

Enter the measurements of the triangle type you've selected. Refer to the schematic if you're unsure which measurements correspond to which fields.

Let the square feet of a triangle calculator automatically find the area of the triangle.
If you want to learn how to find the square feet of a triangle by yourself, then keep scrolling!
How do I calculate the square feet of a triangle?
It depends on what measurements of the triangle you already know. Most commonly, you'd have one of these sets of measurements at your disposal:
 Base and height;
 Three sides (also called SSS);
 Sideangleside (SAS); or
 Anglesideangle (ASA).
Let's look at each triangle type and see how we can calculate its area, $A$.
Base and height
The base and height triangle area formula simply uses the base $b$ and the height $h$:
Three sides
When all three sides $a$, $b$, and $c$ are known, we can use Heron's formula,
where $s$ is the semiperimeter, $s = \tfrac{1}{2}(a+b+c)$.
Sideangleside
The SAS triangle has two sides $a$ and $b$ known, as well as the angle $\gamma$ that lies inbetween $a$ and $b$. Its area formula is pretty simple:
Anglesideangle
The ASA triangle has two angles $\gamma$ and $\beta$ known, as well as the side $a$ inbetween these angles. You can work out its area with:
What is the square feet area of a triangle with sides of 6 feet?
Its area is 15.59 ft²
. Since we know that all three sides are 6 feet long, we can use Heron's formula to work out its area in square feet.
 Calculate the perimeter:
p = 3 × (6 ft) = 18 ft
 Divide the perimeter in half to get the semiperimeter:
s = ½p = 9 ft
 Use Heron's formula:
A = √[ s(s−a)(s−b)(s−c) ]
A = √[ 9 × (9 − 6)³ ]
A = √[ 9 × (3)³ ]
A = 15.59 ft²
How do I determine the square feet of scalene triangle?
If you know it's a scalene triangle, then chances are you already know its side lengths. In that case, you can use Heron's formula to determine the triangle's area:
A = √[ s(s−a)(s−b)(s−c) ]
Here, s
is the semiperimeter, which is half of the triangle's perimeter.