Heron Triangle Area
Heron's formula finds triangle area from the three side lengths alone. It avoids requiring a directly measured height.
Heron Triangle Area
Triangles · 3 inputs
How to use this calculator
- Enter side a in cm.
- Enter side b in cm.
- Enter side c in cm.
- Select Calculate and keep the output unit with the answer.
Before you use the answer
Start with a dimensioned sketch and label the units beside every measurement. Distinguish the outer edge from an internal opening, and distinguish a radius from a diameter. A geometric model is most useful when the shape actually matches the assumptions in the formula.
Every pair of sides must sum to more than the third. Degenerate and impossible triangles are rejected.
Does it save my inputs?
No calculation history is stored by this website. The calculator works locally in your browser. See the privacy policy for hosting and contact details.
Why might a result be approximate?
Measurement uncertainty, ideal-model assumptions and floating-point rounding can all matter. Displaying more digits does not improve the original measurement.
Related calculations
Right Triangle Hypotenuse
The hypotenuse sits opposite the right angle and is always the longest side of a right triangle.
Open calculator ↗Missing Right Triangle Leg
Rearranging Pythagoras finds the missing perpendicular leg when the longest side and one leg are known.
Open calculator ↗Equilateral Triangle Area
An equilateral triangle divides into two matching right triangles, which explains the square-root-of-three factor.
Open calculator ↗