Standard Kitchen Cabinet Sizes
While there are always exceptions to any rule, stock and semi custom lines have some fairly standard kitchen cabinet sizes. Here are some guidelines to use when planning your space for the standard kitchen cabinet sizes you'll most likely run into.
Cabinet sizes vary from line to line, but there are some common themes. One is the three inch increment. This means that cabinet widths are divisible by three, so you can get a 12 inch wide base, a 15, 18, 21, and so on. Depths are kind of along the same lines, with the deepest you'll probably see being 24 inches. Heights vary but still stick to some general parameters.
Standard Kitchen Cabinet Sizes: Base Cabinets
As I just said, base cabinet widths are in three inch increments. What varies from line to line is the smallest and largest cabinet you can get. In the few lines I deal with, I've seen them as small as six inches, and as big as sixty inches. There are some gigantic cabinets out there. I chuckle whenever I see one get ordered as I remember how many tight corners I've taken delivering such monstrosities. The smaller cabinets, nine inches and under, tend to get a little weird in the raised panel door styles. The panel on a nine inch cabinet ends up being about as wide as the stiles and rails. The six inch cabinets I've seen are usually not whole cabinets at all, but pullout spice racks that usually need to be between either adjacent cabinets, or panels; otherwise the stuff on the racks might fall out and jam things up. If you want one of these to match your doors, there are usually filler overlays that you can get that mimics the look of a raised panel.
At about 24 inches, base cabinets start having two doors. Some manufacturers give the option of one door or two in a Base 24 cabinet. The smaller doors are less likely to warp, but there's the chance that one of the doors might open up toward a spot you might be in a lot, and I can tell you from experience that doors opening toward you (like when you're standing at the sink and want to put a plate away) are a royal pain. Similarly, Base 48's lots of times come with the option of being a Coupe or a Sedan (two or four doors) and in these instances I don't think it matters so much which one you pick; you're going to have a door opening toward you whichever way you look at it.
Some manufacturers offer base cabinets in different depths. The standard size is 24 inches, but you can get them in 21, 18, and 12 as well. This is one of the things that sets stock lines apart from semi custom lines. Stock lines have very little in the "different depths" department. Mostly 24 inches with a few 12 inch choices and that's about it.
Standard Kitchen Cabinet Sizes: Wall Cabinets
I'll start with depth here, since most wall cabinets are 12 inches deep. Semi custom manufacturers offer 15 and 18's as well. I don't see a whole lot of 21 inch deep cabinets. 24 inch deep wall cabinets are usually reserved for over the fridge, and come in a limited variety of heights and widths. What's nice about wall cabinets is that a lot of manufacturers let you reduce the depth, and just charge for the bigger size. Say you want a W361821 (that's 36 wide, 18 high, 21 deep) but the closest a manufacturer makes is a similar model that's 24 inches deep. You can reduce the depth to 21 inches, but still have to pay for a 24 inch deep cabinet. So long as they don't charge even more for the modification, it seems a fair trade to me.
Wall cabinet heights vary from 12 inches all the way up to 60, with the bigger ones usually being book cases, or wall cabinets with drawers or garages at the bottoms. If the rest of your kitchen has 42" high wall cabinets, a 60 inch one will sit on the counter and have a top that's flush with the rest of the cabinetry. The usual heights I see for regular wall cabinets (nothing that goes over an appliance, just run of the mill "stick it on the wall" kind) are 30, 36, and 42 inch.
Some manufacturers offer a 33 inch high cabinet, or a 39. Bertch Legacy is one. The 12 inch high cabinets I see are usually in only a few widths. Actually the semi custom like I've run across with the greatest selection of widths (without using any kind of custom modifications) is Kabinart. One customer of mine replaced a soffit with a bunch of 12 inch cabinets all around the kitchen. Most 12 high cabinets are made for over the stove (or range, or cooktop, or whatever word you prefer — hob in England I think) or the fridge, so most of the ones I see in manufacturers' spec books are no narrower than 30 inches.
Speaking of narrow… Like base cabinets, wall cabinets start at 9 inches (with spice pullouts going down to 6) and up to about 48 inches wide. Bigger wall units tend to be smaller units put together, rather than one big cabinet.
Standard Kitchen Cabinet Sizes: Tall Cabinets
Last we come to the tall cabinets. Like the others, they come in a variety of heights, widths, and depths; most semi custom manufacturers don't offer quite the variety that they do in the base and wall cabinets though. Depths are generally 24 inches, sometimes 12. Anything else is usually a reduced depth modification. Heights are in line with their wall cabinet height offerings. Since wall cabinets end up being 54" off the floor, a manufacturer makes their tall cabinets in heights that allow the tops to be the same heights as the wall cabinet tops.
In a kitchen with 42" wall cabinets, for example, the tops of the wall cabinets are 96 inches off the floor. Lo and behold, you'll probably see a 96 inch high utility or pantry cabinet in the spec book as well. To match 30 inch high wall cabinets, you'll need 84 inch high tall cabinets. 36" walls means you need 90" walls. Manufacturers that offer more choices for wall cabinet heights will probably also offer more choices for tall cabinets heights, so that things will match up when they're all installed.
As far as standard tall cabinet widths, I can only say that it depends on the manufacturer. Many only go as big as 36 inches, and as small as 24. Some go down to 15 inches. It all depends on which spec book you're looking at.
Hope that clears some things up for you. Let me know if I've helped or muddied the waters further. Once you get the general idea, it's then a matter of finding out who makes the sizes you'll need in a door style you like.