Triangle Area from Three Sides (Heron's Formula)
Calculates the triangle area from three sides (heron's formula) from the measurements you enter. Use any unit, as long as all inputs use the same one.
Result
- Area
- 14.6969
How to use the triangle area from three sides (heron's formula)
- Enter the side a.
- Enter the side b.
- Enter the side c.
- The results update as you type, or press Calculate.
- Read the area first, then the supporting figures below it.
Formula
√(s(s−a)(s−b)(s−c)), s = (a+b+c)/2
Worked example
For example, with these inputs:
- Side a: 5
- Side b: 6
- Side c: 7
the calculator returns:
- Area: 14.6969
Background
A quick mental estimate before calculating is a powerful check. If a room's floor area comes out at 4,000 square metres or a percentage comes out above 100% when it should not, you know to look again.
In everyday life the same maths shows up in discounts, recipe scaling, renovation measurements and comparing prices per unit. Being comfortable with it saves money and avoids costly measuring mistakes.
Frequently asked questions
How does the triangle area from three sides (heron's formula) work?
It applies this formula: √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).
Guides for this calculator
- How to Calculate Triangle Area from Three Sides (Heron's Formula): A Step-by-Step Guide
- Triangle Area from Three Sides (Heron's Formula) Formula Explained, With Examples
- Triangle Area from Three Sides (Heron's Formula): 5 Mistakes to Avoid
- Triangle Area from Three Sides (Heron's Formula): Your Questions Answered