In snooker, what is the diameter of a standard object ball?

A standard snooker object ball has a diameter of 52.5 millimetres.

Snooker uses balls that are smaller than those used in several other cue sports. The complete set consists of 15 reds, six colours and one white cue ball, all made to the same standard ball size for normal play.

The compact ball diameter suits the narrow pockets and the full-size table used in snooker. Pocket openings, cushions and ball specifications work together to make positional accuracy especially demanding.

People sometimes confuse snooker-ball measurements with pool-ball measurements. Pool balls are commonly larger, while carom billiards uses a different table and equipment specification. Tournament snooker equipment is manufactured to governing-body standards, so professional events use consistent ball dimensions.