Find the area of any triangle two ways: the simple base-times-height method, or Heron's formula when you only know the three side lengths.
How it works
- Choose your knowns: Base & Height or 3 Sides.
- Input the dimensions.
- The calculator computes the geometrical area (using Heron's formula for sides).
Frequently asked questions
When do I use Heron's formula?
When you know all three sides but not the height — common for irregular triangles.
What makes three sides a valid triangle?
Each side must be shorter than the sum of the other two (the triangle inequality).
Do the units matter?
Use consistent units; the area comes out in those units squared.
Can I use this for right triangles?
Yes — for a right triangle, use base × height ÷ 2 where the two legs are the base and height. Heron's formula also works if you know all three sides.
What units should I use?
Any consistent unit — the area comes out in those units squared. If your sides are in meters, the area is in square meters. If in feet, it is in square feet.