# Perimeter of a Circle (by the diameter)

## Description

A perimeter is a path that surrounds a two-dimensional shape.The perimeter of a circle or ellipse is called its circumference. A circle can be defined as the curve traced out by a point that moves so that its distance from a given point is constant. The ratio of a circle’s circumference to its diameter is π (pi), an irrational constant approximately equal to 3.141592654. The length of the circumference of the circle is related to its diameter.

Related formulas## Variables

C | Circumference of the circle (m) |

π | pi |

d | Diameter (m) |