Regular polygon area calculator
Enter the number of sides and the side length to get the area, perimeter, apothem, circumradius and interior angle of a regular polygon.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter number of sides, side length and length unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Area = n × s² ÷ (4 × tan(180°/n)), apothem = s ÷ (2 × tan(180°/n)), circumradius = s ÷ (2 × sin(180°/n)), interior angle = (n − 2) × 180° ÷ n.
Example
Inputs: Number of sides = 6, Side length = 5, Length unit = Centimeters (cm). Result: Area: 64.9519 cm²; Perimeter: 30 cm; Apothem (inradius): 4.3301 cm.
Limits and caveats
- It applies only to regular polygons, with equal sides and equal angles.
- The unit choice only labels the results.
Questions about this tool
What is the area of a regular hexagon?
It is (3√3 ÷ 2) × s², so a hexagon with side 1 has an area of about 2.598. Enter 6 sides in the calculator.
What is the apothem?
The perpendicular distance from the center to the middle of a side. The area equals half the perimeter times the apothem.
What do the interior angles add up to?
(n − 2) × 180°. An octagon totals 1080°, so each angle is 135°.