How to use the Triangle Calculator
Enter base and height using the same length unit to calculate area in square units. Optionally enter the other two side lengths to calculate perimeter. Choose the correct shape or relationship and enter measurements in compatible units. A numeric result is only as accurate as the dimensions supplied.
What this calculator does
Calculate triangle area and perimeter from base, height, and side lengths. It is intended to make the calculation transparent and repeatable: you provide the known values, the calculator applies the relevant relationship, and the result is shown with the units or labels used by the tool.
When this tool is useful
Use the Triangle Calculator when you need a quick, repeatable check and already have the inputs requested by the page. It is useful for comparing scenarios, checking hand calculations, planning a task, or understanding how changing one input affects the result.
How the calculation works
Area uses ½ × base × height, while perimeter is the sum of the three side lengths.
Practical example
For a practical check, enter a small set of values you can verify independently, then compare the calculator’s result with the relationship described above before using it for a larger triangle problem.
Things to keep in mind
- Use compatible units for every dimension.
- The calculator returns mathematical geometry, not allowances for irregular edges, tolerances, or measurement error.
- Round only after the calculation when you need the most accurate intermediate result.