How does the Regular Polygon Calculator work?

Area = (n × s²) / (4 × tan(π/n)) Then: Interior angle = (n−2) × 180° / n Then: Exterior angle = 360° / n Then: Circumradius R = s / (2sin(π/n)); Apothem a = s / (2tan(π/n)).

Can you give an example of how to use the Regular Polygon Calculator?

Example: Input Regular octagon, side 3cm gives a result of Area = (8×9)/(4×tan(22.5°)) = 72/1.657 = 43.46 cm²; Interior angle = 135°.

Is the Regular Polygon Calculator free to use?

Yes — completely free with no registration, download, or subscription required. All calculations happen instantly in your browser.

How accurate is the Regular Polygon Calculator?

Our Regular Polygon Calculator uses verified mathematical formulas and is accurate to multiple decimal places. Results are calculated in real-time using the same methods used by professionals.

Mathematics

Regular Polygon Calculator

Regular Polygon

Number of sides (n)

Side length (s)

A regular polygon calculator computes area, perimeter, interior and exterior angles, circumradius, and apothem for any regular polygon (equal sides and angles).

Symbol	Name	Unit	Description
n	Number of sides	—	—
s	Side length	units	—
A	Area	square units	—

n	Name	Interior angle	Area (s=1)
3	Equilateral triangle	60°	0.433
4	Square	90°	1.000
5	Pentagon	108°	1.720
6	Hexagon	120°	2.598
8	Octagon	135°	4.828
12	Dodecagon	150°	11.196

References

›Regular polygon — Wolfram MathWorld

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Regular Polygon Calculator

Regular Polygon

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Regular Polygon