Regular Polygon Calculator
Calculate area, perimeter, and interior angle of a regular polygon.
About this calculator
The Regular Polygon Calculator on NumberCals is a free, mobile-friendly tool for anyone needing to calculate area, perimeter, and interior angle of a regular polygon. Enter your values in the form below and the result is computed instantly — no sign-up, no installation, no waiting.
Formula used
A = (n·s²) / (4·tan(π/n)); P = n·s; Interior angle = (n−2)·180°/n
What you'll need
- Number of sides (n) (e.g. 6)
- Side length (s) (e.g. 5)
What you'll get
- Area
- Perimeter
- Interior Angle (°)
- Apothem (centre to edge midpoint)
Formula
A = (n·s²) / (4·tan(π/n)); P = n·s; Interior angle = (n−2)·180°/n
Result
Frequently Asked Questions
What's the apothem? +
The perpendicular distance from the centre of the polygon to the midpoint of any side. For a hexagon with side 5, apothem ≈ 4.33.
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