How big is a 3mm tennis chain?

A 3mm tennis chain is 3 millimeters thick, which equates to around 0.12 inches. The size is average for tennis chains, which typically range from 2 to 7 millimeters in thickness. When shopping for a tennis chain, consider the length as well as the thickness. How long the necklace is will determine whether it hits above, at or below your collarbone. Explore a collection of tennis chains on 1stDibs.