# Circumference of a Circle

The circumference of a circle is the distance all the way around the circle. It's the same as the perimeter, but a special word that we only use for the perimeter of a circle. The circumference is always equal to twice the radius of the circle times π (pi), or 2πr.

Here's a proof that this is always true for any circle.

## Learn by doing: figure out the circumference of a plate in your kitchen.

Radius

Diameter

Area of a Circle

More about Geometry

## Bibliography and further reading about circles:

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More Geometry

More about Math

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Copyright 2012-2015 Karen Carr, Portland State University. This page last updated September 2015.

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