Calculate the area of any regular polygon from the number of sides and side length, apothem, or circumradius. Also shows perimeter, interior angle, diagonal count, and comparison table.
<p>The <strong>Regular Polygon Area Calculator</strong> computes the area, perimeter, apothem, circumradius, interior and exterior angles, and number of diagonals for any regular polygon with 3 or more sides. It supports three input modes: side length, apothem, or circumradius—so you can use whichever measurement you have on hand.</p> <p>Regular polygons—shapes with all sides and angles equal—are central to geometry, tiling, architecture, and design. Hexagons tile floors and honeycomb structures, octagons form stop signs, pentagons appear in soccer balls, and dodecagons tile clocks. Calculating their area accurately is essential for flooring estimates, material cutting, landscaping, and engineering applications.</p> <p>The core formula is <strong>Area = ½ × perimeter × apothem</strong>, but deriving the apothem from a side length (or vice versa) requires trigonometry. This calculator handles all the conversions automatically. Enter the number of sides and one measurement, and every other property is computed instantly.</p> <p>A reference table shows properties for all regular polygons from 3 to 12 sides with unit side length, making it easy to compare shapes. A bar chart visualizes how area grows as the number of sides increases (approaching a circle), and another bar chart compares the side length, apothem, and circumradius for your specific polygon. Eight presets let you quickly load common shapes like equilateral triangles, squares, and hexagons.</p>
Regular polygon area work comes up whenever you need more than a rough sketch of a shape. Landscapers estimate paving coverage for hexagonal stones, teachers compare how polygons approach a circle, and designers size badges, signs, and decorative panels with equal sides. In each case, the hard part is not the final multiplication but converting among side length, apothem, and circumradius without mixing up the trigonometry.
This calculator removes that conversion work and shows the rest of the geometry at the same time. You can move between common polygon types, compare how area changes as side count increases, and verify whether your chosen dimensions produce the footprint you expect before you cut material or submit an answer.
Area = ½ × n × s × apothem. Apothem = s / (2 tan(π/n)). Circumradius = s / (2 sin(π/n)). Interior Angle = (n−2) × 180° / n. Diagonals = n(n−3) / 2.
Result: Area ≈ 64.95, Perimeter = 30, Apothem ≈ 4.33
For a regular hexagon with s = 5: apothem = 5 / (2 tan(30°)) ≈ 4.33. Area = ½ × 30 × 4.33 ≈ 64.95.
The area formula for a regular polygon is easiest to use when you know the apothem, because $A = frac{1}{2}Pa$ turns the problem into a clean perimeter-times-height calculation. In practice, though, many problems start with a side length from a drawing or a circumradius from a circular layout. Converting those measurements correctly is where most mistakes happen. This calculator keeps the same polygon definition while switching among all three inputs, so you can see how each measurement describes the same shape from a different angle.
For a fixed side length, adding more sides usually increases the enclosed area because the polygon becomes less sharp and more circle-like. A triangle encloses the least area for a given side length, while large-sided polygons steadily approach the area of a circle with a similar radius. That pattern matters in tiling, packaging, and structural design, where shape efficiency determines how much space you enclose for the edge length you spend.
If your answer looks off, verify that the side count is at least 3 and that you used the intended measurement mode. A side length and a circumradius with the same numeric value do not describe the same polygon, so selecting the wrong mode can shift the area significantly. It also helps to compare the apothem and circumradius in the output cards: for any regular polygon, the apothem should be smaller, and both values should become closer together as the number of sides increases.
A regular polygon has all sides equal in length and all interior angles equal. Examples include equilateral triangles, squares, and regular hexagons.
The apothem is the perpendicular distance from the center of the polygon to the midpoint of any side. It equals the inradius of the inscribed circle.
The circumradius is the distance from the center to any vertex—it equals the radius of the circumscribed circle. Use this as a practical reminder before finalizing the result.
No. This calculator applies only to regular (equilateral and equiangular) polygons. Irregular polygons require different methods.
As a regular polygon gains more sides, it closely approximates a circle with radius equal to the circumradius. The area formula converges to πR².
The formula is n(n − 3) / 2. A triangle has 0, a square has 2, a pentagon has 5, a hexagon has 9, and so on.