# Circumference

linear distance around the outside of a closed curve or circular object

In geometry, circumference is the distance around a closed curve; for example, a circle. It is a special kind of perimeter. The length of the circumference of a circle is often written as ${\displaystyle C}$,[1] with:[2][3]

Circumference of a circle
${\displaystyle C=\pi d}$

where d is the diameter of the circle.

## References

1. "List of Geometry and Trigonometry Symbols". Math Vault. 2020-04-17. Retrieved 2020-09-24.
2. Weisstein, Eric W. "Circle". mathworld.wolfram.com. Retrieved 2020-09-24.
3. "Radius, diameter, & circumference | Circles (article)". Khan Academy. Retrieved 2020-09-24.