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Regular Polygon Calculator

Find the perimeter, area, and angles of a regular polygon.

Introduction

Regular Polygon Calculator — Find the perimeter, area, and angles of a regular polygon. Enter Number of sides, Side length to get an instant, accurate result.

Formula

Perimeter = n×s. Area = (n×s²)/(4×tan(π/n)). Each interior angle = ((n−2)×180)/n. Each exterior angle = 360/n, where n is the number of sides and s is the side length.

Step-by-step

  1. Enter the Number of sides.
  2. Enter the Side length.
  3. Click Calculate to see your result instantly.

Real-world example

Example: With Number of sides = 4, Side length = 5, the Regular Polygon Calculator gives Perimeter: 20, Area: 25, Interior Angle: 90.

Frequently Asked Questions

How are interior and exterior angles related?
They always add up to 180° for each vertex of the polygon.
What is the minimum number of sides?
3 (a triangle) — anything below that is not a valid polygon.
What inputs does the Regular Polygon Calculator need?
You'll need to provide: Number of sides, Side length. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Regular Polygon Calculator?
The Regular Polygon Calculator applies the formula exactly as calculated — Perimeter = n×s. Area = (n×s²)/(4×tan(π/n)). Each interior angle = ((n−2)×180)/n. Each exterior angle = 360/n, where n is the number of sides and s is the side length. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Regular Polygon Calculator free to use?
Yes, the Regular Polygon Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Regular Polygon Calculator

The Regular Polygon Calculator uses a real, verifiable formula — Perimeter = n×s. Area = (n×s²)/(4×tan(π/n)). Each interior angle = ((n−2)×180)/n. Each exterior angle = 360/n, where n is the number of sides and s is the side length. — so results are accurate every time, not an approximation.