Geometry & Trigonometry
Basic
Circumference of a Circle
The perimeter (boundary length) of a circle.
Formula
Variables
rRadius
Example
A circle of radius 5 has circumference C = 2π·5 ≈ 31.4 units.
Did You Know?
The ratio of any circle's circumference to its diameter is always π — a constant that has been computed to trillions of digits.