Circumference = pi(diameter) Pi times diameter

Sometimes to find the diameter, you must multiply the radius by two to get the diameter; the radius is half the diameter and is from the center of the circle to the edge/rim whatever you want to call it. Pi also equals 3.14159265358979323… etc. It goes on forever. But most people just use 3.14.

Circumference = pi(diameter) Pi times diameter

Sometimes to find the diameter, you must multiply the radius by two to get the diameter; the radius is half the diameter and is from the center of the circle to the edge/rim whatever you want to call it. Pi also equals 3.14159265358979323… etc. It goes on forever. But most people just use 3.14.