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Circle calculator

Find radius, diameter, circumference and area from any one known measurement. Calculate arcs, sectors and chords.

Get started

  1. Use the example values or enter your own measurements.
  2. Calculate, then copy the result or download the available details.

Example

Input

Radius 2; central angle 90°

Expected result

Circumference ≈12.5664; arc ≈3.1416

Try it

Good to know

The calculation runs in your browser. Use consistent units in fields with no explicit unit.

Calculation method

Circumference = 2πr. Area = πr². Arc length and sector area scale with the central angle divided by 360°.

A=πr2,C=2πrA=\pi r^2,\qquad C=2\pi r