Triangle Area Calculator
This triangle area calculator can help in determining the triangle area. The basic triangle area formula needs to have a base and height given, but what if we don't have it? How can we calculate the area of a triangle with 3 sides only? The triangle area calculator is here for you. Give it a go! If you are still unsure how to find the area of a triangle, check the description below.
Triangle area formula
A triangle is one of the most basic shapes in geometry. The best known and the most straightforward formula, which almost everybody remembers from school, is:
area = 0.5 * b * h
, whereb
is the length of the base of the triangle, andh
is the height/altitude of the triangle.
However, sometimes it's hard to find the height of the triangle. In that cases, many other equations may be used, depending on what you know about the triangle:

Three sides (SSS)
If you know the lengths of all sides, use the Heron's formula:
area = 0.25 * √( (a + b + c) * (a + b + c) * (a  b + c) * (a + b  c) )

Two sides and the angle between them (SAS)
You can calculate the area of a triangle easily from trigonometry:
area = 0.5 * a * b * sin(γ)

Two angles and a side between them (ASA)
There are different triangle area formulas versions  you can use, for example, trigonometry or law of sines to derive it:
area = a² * sin(β) * sin(γ) / (2 * sin(β + γ))
If you are looking for other formulas or calculators connected with triangles, check out this right triangle calculator, pythagorean theorem calculator, and law of cosines calculator.
How to find the area of a triangle?
Assume that we know two sides and the angle between them:
 Type the first side length. It can be equal to 9 inches in our example
 Enter the second triangle side. Let's choose 5 in.
 Determine the angle between two known sides. For example, 30 degrees.
 Watch our triangle area calculator performing all calculations for you! The area for our case is equal to 11.25 in².
Area of an equilateral triangle
To calculate the area of an equilateral triangle, you only need to have the side given:
area = a² * √3 / 4
Although we didn't make a separate calculator for the equilateral triangle area, you can quickly calculate it in this triangle area calculator. Simply use the subpart for the area of a triangle with 3 sides  as you know, every side has the same length in an equilateral triangle. It's possible to calculate that area also in the anglesideangle or sideangleside version  you probably remember that every angle in the equilateral triangle is equal to 60 degrees (π/3 rad).
Want more?
For areas of different shapes, check the other awesome calculators: