Polygon calculator

Regular polygon area = n × side² ÷ (4 × tan(π/n)). Perimeter = n × side.

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Polygon calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Number of sides

Side length

Answer

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Regular polygon area = n × side² ÷ (4 × tan(π/n)). Perimeter = n × side.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Step-by-step calculation

Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Every side and interior angle must be equal. This is not an area calculator for an irregular polygon.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

Scratch calculator

Check another calculation

Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.

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Updated 2026-09-26

Using Polygon calculator

Regular polygon area = n × side² ÷ (4 × tan(π/n)). Perimeter = n × side.

Every side and interior angle must be equal. This is not an area calculator for an irregular polygon.

Next: Rhombus calculator

A worked example

With number of sides = 6, side length = 2, the area is 10.392304845413264.

Next: Rectangle calculator

Before you use the result

Every side and interior angle must be equal. This is not an area calculator for an irregular polygon.

Example results for number of sides

These examples use Side length: 2. They are reference calculations, not recommended settings.

Number of sides	Area
3	1.73205080757
6	10.3923048454
12	44.7846096908

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ToolOctopus. “Polygon calculator.” Updated 2026-09-26. https://tooloctopus.com/polygon-calculator.

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