Base Cabinet Cut-List Formulas for Any Width
Calculate base-cabinet sides, bottom, shelves, and stretchers from outside width, measured material thickness, joinery, and clearance assumptions.
There is no trustworthy one-size-fits-all cabinet cut list. Component dimensions depend on the construction model: outside box size, actual material thickness, whether the bottom is captured or overlaps the sides, dado depth, back treatment, toe-kick method, shelf clearance, and hardware. The formulas below use a transparent frameless example so each assumption can be replaced instead of hidden.
Define the construction model before calculating parts
The worked model uses a 34 1/2-inch-high carcass, 23 1/4-inch-deep sides, two measured 3/4-inch side panels, a bottom captured between the sides, and two 4-inch top stretchers. The bottom is shown at 22 1/2 inches front to back. Doors, drawers, toe-kick notches, a separate base, back-panel joinery, face frames, hardware, and edge banding are not included.
Those are example decisions, not universal cabinet standards. Write down the outside box dimensions and joinery from the actual design. Then measure the stock where thickness affects captured parts. Nominal 3/4-inch plywood may not measure exactly 0.750 inch, and that difference appears twice across the cabinet width.
- W = desired outside carcass width
- t = measured thickness of one side
- d = dado depth into each side, when used
- c = total shelf side clearance across the opening
Calculate a bottom captured between two sides
For a butt-jointed bottom that fits fully between the sides, subtract both side thicknesses from the outside width. A 24-inch cabinet built with two 3/4-inch sides has a 22 1/2-inch inside span. That span becomes the bottom length and the top-stretcher length in this model.
Keep the front-to-back bottom dimension separate from the width formula. Here it is 22 1/2 inches because the example intentionally sets the bottom back from the 23 1/4-inch side depth. Change that value to match the front reveal, back groove, applied back, nailer, or door system in the real design.
inside span = W − (2 × t)24 − (2 × 0.75) = 22.5 in30 − (2 × 0.75) = 28.5 inAn overlay bottom, full top, face-frame extension, or different side relationship requires a different equation.
Worked dimensions for 18, 24, 30, and 36-inch boxes
This comparison holds the measured side thickness at 3/4 inch and gives each adjustable shelf 1/8 inch of total side clearance. The shelf is also 1/8 inch shallower than the 22 1/2-inch bottom in the related SawNest project examples. Confirm shelf-pin hardware, edge banding, and installation clearance before cutting.
The side panels remain 23 1/4 × 34 1/2 inches because only outside cabinet width changes in this table. Wide shelves may need different material, edging, supports, or a span check; a dimension formula does not establish structural capacity.
| Outside width | Sides, qty 2 | Bottom | Adjustable shelves | Stretchers, qty 2 |
|---|---|---|---|---|
| 18 in | 23 1/4 × 34 1/2 | 22 1/2 × 16 1/2 | 21 7/8 × 16 3/8 | 4 × 16 1/2 |
| 24 in | 23 1/4 × 34 1/2 | 22 1/2 × 22 1/2 | 21 7/8 × 22 3/8 | 4 × 22 1/2 |
| 30 in | 23 1/4 × 34 1/2 | 22 1/2 × 28 1/2 | 21 7/8 × 28 3/8 | 4 × 28 1/2 |
| 36 in | 23 1/4 × 34 1/2 | 22 1/2 × 34 1/2 | 21 7/8 × 34 3/8 | 4 × 34 1/2 |
Adjust the formula when the bottom enters dados
A bottom seated in dados extends past the clear inside faces and into both side panels. If each dado has depth d, add two dado depths to the clear inside span. The equivalent compact formula is W − 2(t − d).
For a 24-inch outside width, 3/4-inch sides, and 1/4-inch-deep dados, the bottom length becomes 23 inches: 24 − 2(0.75 − 0.25). Confirm that the design references the same outside faces, and distinguish dado depth from groove width. The groove width follows the measured bottom thickness and fit requirement; it does not change this across-cabinet length equation.
dadoed bottom = W − 2(t − d)24 − 2(0.75 − 0.25) = 23 in30 − 2(0.75 − 0.25) = 29 inAsymmetrical joinery should be calculated side by side rather than forced into the equal-dado shortcut.
Turn formulas into an auditable cut list
Give each unique component a stable part ID, record finished dimensions in one declared order, and keep material thickness, quantity, grain direction, and edge treatment visible. Do not bury kerf or edge trim in the component formula: those are stock and process allowances applied after the finished parts are known.
Reconcile the generated quantity against the drawing, then run the rectangles through a sheet layout. A valid formula can still produce a poor purchasing plan, and an efficient layout can still be wrong if a part or joinery assumption is missing. The 24-inch and 30-inch SawNest examples show the same model at two widths so both the arithmetic and resulting sheet use can be inspected.