3. How much storage do you need?A lot of this depends on your kitchen layout. If you have space for a lot of cabinetry in the kitchen, island storage may not be a priority. If this is to be your main prep area, the sink and other appliances may have to come first, but try to make room for prep utensils and cutting boards near the sink. "Typically, two 24-inch base cabinets back to back will accommodate most under-island functions," says Justrich. "But make sure that your island isn't too big, with extra space in the middle." Ahmann suggests making your island 3 feet wide, as that tends to look best — although sometimes a width of 2 feet is the best fit. The length can be as few as 4 feet, but he suggests planning for at least 7 feet if you need to accommodate a sink, a dishwasher and a cooktop.