Turn a cabinet opening into a drawer box cut list. Enter the opening, the clearances your slides need, the drawer-side stock and the bottom groove, and the calculator returns the box size, the side and front/back lengths, and the bottom panel.
Drawers go wrong when they are sized from a drawing instead of the cabinet that was actually built. Measure the opening after the face frame or the cabinet sides are in place: width between the surfaces the slides mount to, height of the opening, and depth from the front edge to the back or to whatever stops the drawer.
The calculator then subtracts the slide clearance, a little headroom and a little back clearance to get the box, and works out the parts for a simple butt-jointed box with the front and back captured between the sides and the bottom in a groove.
box W = opening W − slide · box H = opening H − top · box D = opening D − back
sides = box D · front/back = box W − 2T · bottom = (box W − 2(T − groove)) × (box D − 2(T − groove))
The bottom size reaches exactly to the bottom of the grooves. In practice, cut it about 1/16 in smaller in each direction so it drops in without forcing, and so a solid-wood bottom has room to move.
Defaults used: 1 in total slide clearance, ½ in top and back clearance, ½ in sides with a ¼ in deep groove, opening 24 in deep.
| Opening W × H | Box W × H × D | Sides (2) | Front & back (2) | Bottom (to groove) |
|---|---|---|---|---|
| 12 × 4 in | 11 × 3.5 × 23.5 | 23.5 in | 10 in | 10.5 × 23 |
| 15 × 6 in | 14 × 5.5 × 23.5 | 23.5 in | 13 in | 13.5 × 23 |
| 18 × 6 in | 17 × 5.5 × 23.5 | 23.5 in | 16 in | 16.5 × 23 |
| 21 × 8 in | 20 × 7.5 × 23.5 | 23.5 in | 19 in | 19.5 × 23 |
| 24 × 10 in | 23 × 9.5 × 23.5 | 23.5 in | 22 in | 22.5 × 23 |
| 30 × 10 in | 29 × 9.5 × 23.5 | 23.5 in | 28 in | 28.5 × 23 |
The default 16 × 6 × 24 in opening. Box 15 × 5.5 × 23.5 in. Sides 23.5 in, front and back 14 in, bottom 14.5 × 23 in to the groove bottoms — cut it at about 14 7/16 × 22 15/16 in.
A deep file drawer with ⅝ in sides. Opening 21 × 8 × 22 in, 1 in slide clearance, ¾ in top, 1 in back, ⅝ in stock with a ¼ in groove. Box 20 × 7.25 × 21 in; front and back 18.75 in; bottom 19.25 × 20.25 in.
A metric kitchen drawer. Switch units to millimetres. Opening 450 × 150 × 500 mm, 26 mm slide clearance (13 mm per side), 20 mm top, 10 mm back, 15 mm stock, 6 mm groove. Box 424 × 130 × 490 mm; front and back 394 mm; bottom 406 × 472 mm.
So the drawer can be tipped in and out and the slides can move freely. Undermount slides often need more room under the box, which you would add to the top clearance figure.
The longest standard length that fits the inside depth of the cabinet. Box depth is often the slide length plus a little, but follow the slide maker’s guidance.
Yes. Set the groove depth to the full stock thickness and the bottom size equals the outside of the box. That is not the layout this calculator assumes by default.
½ in for most drawers, ⅝ in for wider or heavier ones. ¼ in plywood bottoms are common up to about 18 in wide; heavier drawers want ½ in.