Sink size always depends on the size of the base cabinet. While measuring the size, the rule is to cut 2 or 3 inches from the cabinet size. So if you have a 30 inch cabinet, the sick would probably be 28 or 27 inches. But if you are thinking of placing a 30 inch sink into a 30 inch cabinet, in that case, the apron sink may fit nicely onto your base Cabinet.