Original: Modern billiard balls are made from phenolic resin or other highly resilient plastics , are normally 61.5 mm ( 27 â 16 in ) in diameter , weigh between 205 and 220 grams ( 7.23 -- 7.75 ounces ; 7.5 is average ) , and are significantly larger and heavier than their pocket billiards counterparts .
Simplified: The size of carom billiards balls is normally 61.5 mm ( 27 â 16 in ) in diameter . They weigh between 205 and 220 grams ( 7.23 -- 7.75 ounces ; 7.5 is average ) , and are quite a bit larger and heavier than the balls used for pool games .