There is no hard and fast rule for size, but architect Duo Dickinson recommends that an island be at least 4 feet long and a little more than 2 feet deep, with ample room to move around it. "Unless your kitchen is at least 8 feet wide and more than 12 feet long, don't even think about an island," he says.
That means there should be at least 36 inches between and island's the perimeter and the cabinetry or appliances that surround it. The National Kitchen and Bath Association recommends 42 inches, or 48 inches if two cooks are using the room—not an uncommon situation in many families.
Keep these figures in mind when some one tells you that they just have to have an island in the tiny galley kitchen.