How it works
Find triangle area from three sides. Each pair of sides must sum to more than the remaining side.
s = (a+b+c)/2; A = √[s(s−a)(s−b)(s−c)]
Worked example
Show example inputs and result
Side a: 3 · Side b: 4 · Side c: 5.
- Area
- 6
- Perimeter
- 12
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy