With the exception of custom cabinets, widths of cabinets are in increments of three inches, starting at 6 or 9 inches, then increasing to 12, 15, 18, and so on. Base cabinets will typically be 34.5 inches tall, with 4.5 inches of that being the toe kick at the bottom, and 24 inches deep, not including the cabinet door. Countertops are generally around 1.5 inches thick, so the top of the countertop is usually 36 inches off the ground.
As with the bases, the widths of the upper cabinets are in increments of three inches. They are typically 12 inches deep, again, not including the cabinet door. The heights of the uppers typically range from 30 inches and 42 inches, again with increments of three inches between heights. Many of the houses we get cabinets from have high vaulted ceilings, so a lot of the uppers we get are 42 inches.
If you have standard eight-foot ceilings, you can use 42-inch uppers without crown molding on the top. If you put the uppers right against the ceiling, you will have enough between your countertop and the bottom of your upper cabinets so that it will work. You will end up with 18 inches between the countertops and the upper cabinets. We used 42-inch uppers in our first house, and it didn’t look like much space when we drew it out on the wall, but I can assure you that 18 inches really was plenty. Remember that your uppers are typically sitting a foot back from the edge of the countertop. There aren’t really many situations in which you’d want to stick something under an upper that’s 18 inches tall, so it will usually work just fine.