Math July 13, 2026 · 8 Min Read

Regular Polygon Calculator – Guide & Formulas

Calculate the area, perimeter, interior angles, and apothem of any regular polygon with 3 to 100 sides.

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Put these formulas into practice with our instant, step-by-step Regular Polygon Calculator.

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Use our free **Regular Polygon Calculator** to **calculate regular polygon area**, **perimeter**, **apothem**, and **interior angles** for any n-sided shape. This **polygon area solver** helps you find all properties of **regular polygons** from 3 to 100 sides with step-by-step results. Whether you need a **polygon apothem calculator** for architecture or a **polygon interior angles calculator** for geometry class, this tool provides accurate **regular polygon formula** calculations. 100% free — no signup required!

Key Takeaway

Use the free Regular Polygon Calculator to calculate the area, perimeter, interior angles, and apothem of any regular polygon with 3 to 100 sides. Get instant results with step-by-step explanations.

How to Use the Regular Polygon Calculator

  1. Enter the number of sides (n) of your polygon (minimum 3).
  2. Enter the side length of each side.
  3. Review the **regular polygon area calculator** result using A = (n × s²) / (4 × tan(π/n)).
  4. Check the **polygon perimeter calculator** result (P = n × s).
  5. View the **polygon apothem calculator** result (a = s / (2 × tan(π/n))).
  6. Examine the **polygon interior angles calculator** showing each angle and the total sum.
  7. Compare the **regular polygon vs circle area** as the number of sides increases.

The Formula

Area = 0.25 * n * s^2 / tan(pi / n)

Variable Definitions

  • n: The number of sides (degree of polygon)
  • s: Length of each individual side
  • A: Total calculated surface area
  • P: Total boundary perimeter

Sizing an Octagonal Stopping Sign

Calculate the total metal area of an 8-sided regular stop sign with 10-inch sides.

  1. Step 1: Set number of sides n = 8 and side length s = 10 inches.
  2. Step 2: Calculate perimeter: 8 * 10 = 80 inches.
  3. Step 3: Apply the general regular polygon formula: 0.25 * 8 * 10² / tan(180/8) ≈ 482.84 square inches.
  4. Step 4: The face area of the stop sign is approximately 482.84 square inches.

Frequently Asked Questions

What is the formula for the area of a regular polygon?

The **regular polygon formula** is A = (n × s²) / (4 × tan(π/n)), where n is the number of sides and s is the side length. Use our free **Regular Polygon Calculator** to compute it instantly.

Is this regular polygon calculator free to use?

Yes, this **free regular polygon calculator online** is 100% free with no signup required. It provides instant results with step-by-step breakdowns for area, perimeter, apothem, and angles.

What is a "regular" polygon?

A polygon is regular if all its sides are equal in length (equilateral) and all its interior angles are equal in measure (equiangular). Our **n-sided polygon calculator** handles polygons from 3 to 100 sides.

How do you find the sum of interior angles?

The sum of interior angles for any n-sided polygon is (n - 2) × 180 degrees. Each individual interior angle in a regular polygon is (n - 2) × 180 / n.

What is the apothem of a regular polygon?

The apothem is the perpendicular distance from the center to the midpoint of any side. It is calculated as a = s / (2 × tan(π/n)). Our **polygon apothem calculator** computes this automatically.

What happens as the number of sides approaches infinity?

As n increases towards infinity, the regular polygon converges to a perfect circle. The **regular polygon vs circle area** comparison shows this — a 100-sided polygon is nearly indistinguishable from a circle.

How do I calculate the perimeter of a regular polygon?

The **polygon perimeter calculator** formula is P = n × s, where n is the number of sides and s is the side length. This is simply the total length of all sides.

What is the circumradius of a regular polygon?

The circumradius is the distance from the center to any vertex. It is calculated as R = s / (2 × sin(π/n)). The **polygon circumradius calculator** in our tool provides this value.

What are common regular polygon applications?

Applications include floor tiling (hexagons), stop signs (octagons), bolt heads (hexagons), nuts, architectural windows, decorative patterns, and computer graphics polygonal meshes.

How accurate is this regular polygon geometry calculator?

This **polygon area solver** uses IEEE 754 double-precision floating-point arithmetic and trigonometric functions, providing results accurate to multiple decimal places. For any practical application, this precision is more than sufficient.