Under World Pool-Billiard Association (WPA) official gear specs, pool balls weigh from 5.5 to six oz (160 to 170 g) and have a diameter of 2.25 inches (57.15 mm), plus or minus 0.005 inches (0.127 mm). The World Pool-Billiard Association (WPA) publishes the world standardized rules. Game Rules for… Six-pocket. The item of the game is easy: to be the first player to bank 5 balls in any order (eight balls when played with a full rack).