Regular polygon calculator

For any n-sided regular polygon (all sides equal, all angles equal), enter the number of sides and one of: side length, circumradius (R) or apothem (a).

Side length (s)
0
Perimeter
0
Apothem (a)
0
Circumradius (R)
0
Area
0
Interior angle
0°
Central angle
0°
Exterior angle
0°

Formulas

  • Interior angle: (n − 2) × 180 / n
  • Central angle: 360 / n
  • Exterior angle: 360 / n
  • Apothem from side: a = s / (2 tan(π/n))
  • Circumradius from side: R = s / (2 sin(π/n))
  • Area: A = ¼ · n · s² · cot(π/n) = ½ · n · s · a