Heron's Formula Triangle Area Calculator
Enter the lengths of all three sides of a triangle to calculate its area using Heron's Formula.
Heron's Formula Triangle Area Calculator
Calculate a triangle's area from its three side lengths using Heron's Formula, with an automatic check that the three sides can actually form a valid triangle.
Heron's Formula finds a triangle's area purely from its three side lengths, without needing an angle or height. This calculator also validates that the three lengths you enter can actually form a triangle before computing the area.
Example
- With the default values shown above, this calculator returns: Valid Triangle (1 = Yes, 0 = No) ≈ 1; Semi-Perimeter ≈ 9.00; Triangle Area ≈ 14.70.
Frequently Asked Questions
What is Heron's Formula?
For a triangle with sides a, b, c and semi-perimeter s = (a+b+c)/2, the area equals the square root of s(s−a)(s−b)(s−c).
Why does the calculator check for a 'valid triangle'?
Three side lengths only form a real triangle if each side is shorter than the sum of the other two (the triangle inequality). If not, the 'Valid Triangle' result shows 0 and the area is shown as 0 rather than an invalid number.