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Regular Polygon Calculator

Calculate the area, perimeter, interior angle, and apothem of any regular polygon (3-12 sides) from its side length or circumradius. Free online polygon calculator.

Number of Sides

6
312

Known Measurement

Your Results

Results are also pinned to the bottom of your screen.

Regular Polygon Properties

Area

93.5307

square units

Perimeter

36

units

Sides (n)6
Side Length6
Interior Angle120°
Apothem5.1962
Circumradius6

Formulas Used

  • Area = (n × s²) / (4 × tan(π/n)) = (6 × 6²) / (4 × tan(0.5236)) = 93.5307
  • Perimeter = n × s = 36
  • Interior angle = (n − 2) × 180° / n = (6 − 2) × 180° / 6 = 120°
  • Apothem = s / (2 × tan(π/n)) = 5.1962

Quick Answer

To calculate regular polygon properties with n sides of length s: Area = (n x s^2) / (4 x tan(pi/n)). Perimeter = n x s. Interior angle = (n - 2) x 180 / n degrees. Apothem = s / (2 x tan(pi/n)). For a regular hexagon with side 6: Area = 93.53 square units, Perimeter = 36 units, Interior angle = 120 degrees, Apothem = 5.20 units.

Key Facts

  • Formula: Area = (n x s^2) / (4 x tan(pi/n))
  • Formula: Interior angle = (n - 2) x 180 / n degrees
  • Formula: Apothem = s / (2 x tan(pi/n))
  • A regular hexagon with side 6 has area 93.53 and perimeter 36
  • As n grows, a regular polygon approaches a circle of the same circumradius
  • The apothem is the distance from center to the midpoint of any side
  • Area from circumradius R: Area = (n/2) x R^2 x sin(2 x pi/n)
  • The sum of interior angles of any polygon is (n - 2) x 180 degrees

Frequently Asked Questions

How do I calculate the area of a regular polygon?

Use Area = (n x s^2) / (4 x tan(pi/n)), where n is the number of sides and s is the side length. For a hexagon (n = 6) with side 6: Area = (6 x 36) / (4 x tan(30 degrees)) = 216 / 2.309 = 93.53 square units. Equivalently, Area = (1/2) x perimeter x apothem.

What is the apothem of a polygon?

The apothem is the perpendicular distance from the center to the midpoint of any side. It equals s / (2 x tan(pi/n)). For a hexagon with side 6, the apothem is 6 / (2 x 0.5774) = 5.20 units. Area = (1/2) x apothem x perimeter.

What is the interior angle of a regular polygon?

Interior angle = (n - 2) x 180 / n degrees. Triangles: 60 degrees. Squares: 90. Pentagons: 108. Hexagons: 120. The sum of all interior angles is always (n - 2) x 180 degrees, and each exterior angle is 360 / n.

How do I calculate a polygon from the circumradius?

The circumradius R is the distance from center to any vertex. Side length s = 2 x R x sin(pi/n), then use the standard formulas. For area directly: Area = (n/2) x R^2 x sin(2 x pi/n).

Why does a hexagon tile perfectly but a pentagon does not?

Regular polygons tile a plane only when their interior angle divides 360 evenly. The hexagon angle is 120 degrees (360 / 120 = 3), so three fit around a point. The pentagon angle is 108 degrees, which leaves a 36-degree gap.

What is a regular polygon?

A polygon where all sides are equal and all interior angles are equal. Examples: equilateral triangle (3), square (4), regular pentagon (5), regular hexagon (6), up to the regular dodecagon (12). This calculator covers n = 3 through 12.