Regular Polygon Calculator
Area, apothem, radii and angles for any n-gon. Results update as you type.
Enter dimensions
Results
Enter your dimensions above and the results appear here.
About the Regular Polygon Calculator
The regular polygon calculator is a free online tool: area, apothem, radii and angles for any n-gon. Enter number of sides (n) and side length (a) and the results update instantly, alongside a labelled diagram so you always know which measurement goes where.
Choose your input unit (mm, cm, m, km, in, ft or yd) and optionally show the results in a different one: lengths, areas and volumes are converted correctly. Every answer shows the formula behind it, and the calculation runs in your browser, so nothing is uploaded.
Regular Polygon Calculator example
Number of sides (n) = 6sides
Side length (a) = 5 cmArea = 64.9519 cm²
Perimeter = 30 cm
Apothem = 4.3301 cm
Circumradius = 5 cm
Interior angle = 120 °
Exterior angle = 60 °How to use the Regular Polygon Calculator
- Pick the unit your measurements use. All dimensions must share the same unit.
- Enter number of sides (n) and side length (a). Focus a field to highlight the matching label on the diagram.
- Read the results as you type. The largest card is the main answer; the others are the related measurements.
- Copy a single value, copy everything, or share a link that keeps your inputs.
Regular Polygon Calculator FAQ
What formulas does the regular polygon calculator use?
A = n·a² / (4·tan(π/n)); Apothem = a / (2·tan(π/n)); R = a / (2·sin(π/n)); Interior angle = (n−2)·180°/n.
What is the area of a regular hexagon?
For side a it is (3√3/2)a² ≈ 2.598a². Enter n = 6 above for any side length.
Can I use different units?
Yes. Pick the input unit and, if you like, a different output unit. Area results are shown in squared units and volumes in cubed units.
Is this regular polygon calculator free and private?
Yes. It is free with no sign-up, and calculations happen on your device, so your numbers are never sent to a server.
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