How to Build a Cabinet Carcass Cut List from Scratch

Building a custom cabinet starts not with a saw, but with a spreadsheet or a notepad. Whether you are using a table saw or a track saw, your final product is only as accurate as your initial cut list. For woodworkers moving beyond basic furniture, mastering the math of a carcass allows for consistent, professional results. In this guide, we will break down the geometry of a standard base cabinet, accounting for material thickness, assembly methods, and hardware clearances. Once you have these dimensions, you can input them into OptimalLayout to minimize waste across your sheets of plywood or MDF.

Standard Dimensions and Material Selection

For most professional and high-end hobbyist projects, 18 mm (approximately 3/4 inch) sheet goods are the industry standard for the carcass. This thickness provides the structural integrity needed to support stone countertops and the screw-holding strength required for European-style hinges. While 15 mm or 16 mm materials exist, they often lack the rigidity for larger units. Selecting a consistent thickness is vital because every calculation in your cut list depends on it.

In our example, we will design a standard base cabinet with an external width of 600 mm, a height of 720 mm (excluding the toe-kick legs), and a depth of 560 mm. These dimensions are common in international kitchen design as they allow for a standard 600 mm deep countertop with a slight overhang. When planning, always measure your actual board thickness with calipers; '18 mm' plywood can often measure 17.2 mm or 18.5 mm, and that small discrepancy can stack up across multiple cabinets.

Choosing Your Cabinet Construction Method

There are two primary ways to join the main carcass box: Sides-Between-Top-Bottom or Top/Bottom-Between-Sides. For kitchen base cabinets, the almost universal standard is Top/Bottom-Between-Sides. In this configuration, the two vertical side panels (the gables) run the full height of the unit, and the bottom panel is sandwiched between them. This is preferred because the weight of the cabinet contents is transferred through the bottom panel directly into the side panels and then to the legs.

Using this method, the height of your internal horizontal components must be deducted from the overall width. If your total cabinet width is 600 mm and you are using 18 mm sides, your bottom panel width will be 600 mm minus 36 mm (two thicknesses), resulting in 564 mm. This logic applies to any internal stretchers or fixed shelves as well. Keeping the sides full-height also makes it easier to hide end-grain or raw plywood edges if the side of the cabinet is visible.

Calculating the Side Gables and Depth

The side panels are the largest components. For our 720 mm high cabinet, the side gables will be exactly 720 mm by 560 mm. However, we must consider the back panel. A common professional approach is to rebate the back panel into the sides. If you are using a 6 mm plywood back, you might cut a 12 mm deep groove (rebate) into the back edge of the side panels. This 'inset' back provides a void for uneven walls and allows for the use of hanging brackets.

If you use a 12 mm deep rebate for a 6 mm back, you do not necessarily change the external depth of the side panel, but you must realize that the internal usable depth of the cabinet is reduced. If the rebate is 12 mm from the back edge, your bottom panel and top stretchers must be narrower than the sides to avoid hitting the back panel. In our example, 560 mm minus 12 mm equals a component depth of 548 mm for the bottom and stretchers.

The Bottom Panel and Top Stretchers

Modern base cabinets often replace a full solid top panel with 'stretchers' or 'rails' to save material and weight. These are usually 100 mm wide strips of the same 18 mm material. You will need two: one at the front (mounted vertically or horizontally) and one at the rear. These provide the lateral bracing to keep the cabinet square and offer a surface to screw upward into the countertop.

Let us summarize the core components for our 600 x 720 x 560 mm cabinet so far:

• 2x Side Panels: 720 mm x 560 mm
• 1x Bottom Panel: 564 mm x 548 mm
• 2x Top Stretchers: 564 mm x 100 mm
• 1x Back Panel (6 mm ply): 576 mm x 708 mm (assuming 6 mm inset into rebates)

Integrating the Toe-Kick and Legs

In modern cabinetry, the carcass usually sits on plastic adjustable legs, which are later hidden by a toe-kick (or plinth). The standard height for this is 100 mm to 150 mm (approx 4 to 6 inches). If you prefer a built-in 'ladder base' or a notched-out toe-kick in the side panels, you must include those dimensions in your side panel height. If you notch the sides, the gables would increase from 720 mm to 820 mm, with a 100 mm x 50 mm rectangle cut out of the front bottom corner.

Using separate plastic legs is highly recommended for international standardizing. It allows you to level the cabinets perfectly on uneven floors before clipping the plinth board into place. In your OptimalLayout file, remember to add the plinth as a long, narrow strip. For a run of three 600 mm cabinets, your plinth would be one continuous piece of roughly 1800 mm by 100 mm.

Internal Shelving and Clearance

Adjustable shelves require a small amount of 'wiggle room' so they don't scratch the sides of the cabinet during installation. If the internal width is 564 mm, a shelf should be cut at 562 mm or 563 mm. This 1 mm or 2 mm tolerance is crucial for ease of use. Additionally, the depth of the shelf should be at least 10 mm shallower than the internal depth (e.g., 530 mm) to allow for door hinges and the back panel.

If you are planning for drawer slides instead of shelves, ensure your internal width is exactly 564 mm. Most high-quality drawer runners require exactly 25 mm or 26 mm of total clearance (12.5 mm to 13 mm per side). If your carcass is not perfectly square or your material is thicker than 18 mm, your drawers will bind. This is why precise cut lists are the foundation of any project involving moving parts.

Door Overlays and Final Calculations

The final step is the door. In a 'full overlay' design, the door covers almost the entire front face of the carcass. To prevent doors from touching each other in a row of cabinets, you typically subtract 2 mm from each side. For our 600 mm wide cabinet, the door width would be 596 mm. For the height, if the carcass is 720 mm, a door height of 716 mm allows for a 2 mm gap at the top and bottom.

When you have compiled all these numbers, review them one last time. Check that you have accounted for the 'kerf' (the width of the saw blade, usually 3 mm) when estimating how many sheets you need. Tools like OptimalLayout handle this kerf calculation automatically, ensuring that when you get to the workshop, every piece fits exactly正如 planned. Accuracy at this stage avoids the frustration of realizing a panel is one material-thickness too short midway through glue-up.