About the Regular Polygon Calculator
Area, perimeter, interior angle, apothem and circumradius of any regular polygon from the number of sides and side length.
Also known as: polygon area, hexagon area, pentagon calculator, octagon calculator, interior angle of polygon, regular polygon.
How to use this calculator
- Enter number of sides, side length.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
A = n·s² / (4·tan(π/n)) · interior angle = (n − 2)·180°/n
Worked example
Using the values pre-filled in the calculator above:
- Number of sides = 6
- Side length = 4
the calculator returns:
- Area: 41.569219
- Perimeter: 24
- Interior angle: 120 °
- Sum of interior angles: 720 °