How is the area of a regular polygon calculated?

Area = (n × s²) ÷ (4 × tan(π ÷ n)), where n is the number of sides and s is the side length. Every side is equal in a regular polygon.

The apothem is the perpendicular distance from the centre of the polygon to the midpoint of a side. It equals the radius of the inscribed circle.

Is my data sent anywhere?

No — every calculation runs locally in your browser and nothing is uploaded.

Polygon Area Calculator

Area, perimeter and angles of any regular polygon.

Regular polygon calculator

Enter the number of sides and the side length of any regular polygon and this tool returns its area, perimeter, interior angle, apothem (inradius) and circumradius.

A regular polygon has equal sides and equal angles, so its area follows the formula (n × s²) ÷ (4 × tan(π ÷ n)). Everything is computed in your browser — no data leaves your device.