Stock, or store cabinets, are what you see if you go to a large home improvement store. Each store will typically have a very basic, unfinished cabinet line that is stocked in store and ready to purchase and take home that day. These are usually your cheapest option, but selections are very limited. Most of the time these will need to be finished either by you or by a contractor. Don't expect anything spectacular, these are usually cabinets in their most basic form. Drawer fronts are typically made from glued up strips of wood instead of one single piece of wood. Doors are usually paneled doors instead of raised wood panel doors. The carcasses of the cabinets will typically be cut from particle board, and if there is a back panel it is usually 1/8″ hard-board. Countertop fastening brackets will be small, plastic corner brackets with a single screw hole for attaching to the counter.
Typically, stocked cabinets are offered in extremely limited sizes, and while most cabinets are offered in 3″ increments, some stock cabinets may only be available in 6″ increments. This is important when it comes to the overall layout of your kitchen remodel, because stock cabinets are mass-produced to the same size and specifications with no regards as to where they go. You will usually need fillers and end panels to create a finished look when using stock cabinets. The end of each cabinet that is exposed, on both the upper and the base cabinets, will need to be finished to match the front of the cabinets. This will include cutting and fitting finished panels onto the cabinet carcass itself. Keep in mind that if you are running your cabinets wall to wall, then finishing the ends is not important since the wall will hide the ends.
Special Order Cabinets
The upgrade from store cabinets would be ordering them from your local home improvement store or local lumberyard. Quality will be much noticeably higher than stock cabinets, but your options are still somewhat limited as to what you can order. Expect to see laminated interiors in either white or maple color, solid wood drawers and doors, and upgrades such as soft close hinges or soft close drawer slides. These cabinets will come finished and ready to install. Typically, these will be offered in all 3″ increments, usually ranging from 12 inches wide to 36 or even 48 inches wide. Doors and drawer fronts may be somewhat customizable in terms of styles and colors, but options are still limited. Still expect 1/2″ thick carcasses (the box part of the cabinets) and 1/8″ to 1/4″ thick cabinet backs.
Semi custom cabinets are usually offered by specialty shops which deal a specific line of cabinets, but don't make them themselves. The customer will be able to choose the color, finish, style of doors and drawers, as well as many upgrades such as ball bearing slides and soft close hinges. The dealer will work with you and will also include any fillers or other pieces that might be needed to properly install the cabinets. Although you can often choose your own colors, etc, the dealer will have limited options because they can offer only what their supplier offers. A semi-custom cabinet dealer will usually be able to offer installation of the cabinets as well and combine it into one lump sum for you.
Custom Cabinets will almost always be the best quality cabinets that you can find. The cabinet company will usually visit your kitchen or bathroom and take field measurements themselves, and together with you, will design a functional layout for your project. In terms of quality, the cabinetmaker has to make each unit individually, so quality will be very high. Cabinet carcasses will typically be made out of 5/8″ or 3/4″ material, whether it's a laminate material for ease of cleaning, or a hardwood plywood, it will be substantially stronger than particle board or medium density fiber-board. For cabinet backs you will typically see 1/2″ thick material, with thicker areas specifically manufactured for mounting screws. The tops will always incorporate a countertop fastening strip at the front and rear of base cabinets, which you won't see in stock cabinets. As far as design and aesthetics go, the only limitations are your imagination and budget. Almost anything is possible because your cabinets will be made specifically just for you. You have complete access to options such as pull-out slides, trash organizers, limitless hardware choices, pantry organizers, and much more. The cabinetmaker will often install these cabinets themselves too, saving you the headache of doing it yourself. While obviously more expensive, you can design and get exactly what you want, instead of settling for what you can find.