Heron's Formula Calculator
The area of a triangle from the lengths of its three sides.
Result
Area
6.00
Perimeter
12.00
How it works
Area = √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2
Heron’s formula finds a triangle’s area from its three sides alone — no height needed. s is the semi-perimeter, half the total of the sides.
Advertisement
Frequently asked questions
When do I use Heron’s formula?
When you know the three side lengths but not the height — it gives the area directly.
Why might it return zero?
If the sides cannot form a triangle (one side ≥ the sum of the other two), there is no valid area.
Advertisement