Polygon Perimeter Calculator

Work out polygon perimeter instantly with clear inputs, formula shown and shareable results.

About Polygon Perimeter Calculator

For a regular polygon every side is the same length, so the perimeter is simply the number of sides times the side length. The apothem and circumradius follow from the central angle 2π/n.

Formula

Perimeter

P = n × s

Worked example

With the default values below, Polygon Perimeter Calculator returns Perimeter of 32.0000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Number of sidesaccepts 3–1,000: 8
Side lengthminimum 0: 4

Results

Perimeter: 32.0000
Area: 77.2548
Apothem: 4.8284
Circumradius: 5.2263

Step by step

1Values used
2Perimeter
3Perimeter= 32.0000
4Area= 77.2548
5Apothem= 4.8284
6Circumradius= 5.2263

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What about an irregular polygon?

Then you must add the individual side lengths; there is no shortcut. The shoelace calculator handles irregular shapes from coordinates.

How is the circumradius found?

Each side subtends a central angle of 2π/n, giving s = 2R·sin(π/n) and hence R = s / (2·sin(π/n)).