If you mean the official size of the playing area on the table...
"The rules of snooker state that a regulation full-sized table should have a playing surface of 5 feet 9½ inches x 11 feet 8½ inches. The height of the table from the floor to the top of the cushion rail officially must be between 2 feet 9½ inches and 2 feet 10½ inches." (WPBSA)