Measure of the curved line that forms a circle.

### Formula

The formula for the circumference *C* of a circle with radius *r* is: *C* = 2π*r*.

The formula for the circumference *C* of a circle of diameter *d* is: *C* = π*d*.

Measure of the curved line that forms a circle.

The formula for the circumference *C* of a circle with radius *r* is: *C* = 2π*r*.

The formula for the circumference *C* of a circle of diameter *d* is: *C* = π*d*.