The bottom shelves, used for heavy items, should be 16-18 inches deep and about 18-24 inches apart. Eye-level shelves should be 12-14 inches deep and spaced 14-16 inches apart to fit items like cereal boxes and canisters. Shelves for spices and cans need no more than 6 inches front to back. When planning for items you commonly store, add 2 inches of vertical space so you can tip or slide things in and out easily.