Triangle Area Calculator
Choose the method that matches your data: (1) base and height, (2) all three sides (Heron formula), (3) two sides and the included angle between them. You can give the angle in degrees or radians.
Enter values — the result shows live here.
How to use
- Choose a method above.
- Base-height: Value 1 = base, Value 2 = height.
- Heron: enter the three sides in Value 1, 2 and 3.
- SAS: Value 1 and 2 = two sides, Value 3 = the angle between them.
Note: Heron formula: s = (a+b+c)/2, Area = square root of (s(s-a)(s-b)(s-c)). The three sides must follow this rule: the sum of any two must be greater than the third (triangle inequality), otherwise no triangle exists.
Good to know
- For right triangles, base and height can simply be the two shorter sides.
- Heron's method fails when the sides cannot form a triangle — the tool will warn you instead of guessing.
- Keep your units consistent: if sides are in metres, the area comes out in square metres.
- In the SAS method, the angle is the one between the two sides you entered, not any other angle.