Drawer Box Size Calculator (Side-Mount & Undermount Slides)

How it works

side-mount: box width = opening − 25.4 mm, height = opening − 25 mm, depth = slide length ≤ cabinet depth − 25 mm · undermount: width = opening − 10 mm (brand-specific), depth = slide length exactly · front/back = box width − 2 × side thickness · bottom = inner size + 2 × groove depth − 1 mm

A drawer box is sized backwards from the opening and the hardware: side-mount ball-bearing slides need exactly half an inch on each side, which makes the box an inch narrower than the opening, and they come in fixed lengths so the box depth follows the longest slide the cabinet can take. Undermount slides hide beneath the box and instead demand a precise box depth and a recessed bottom for their locking clips, with width allowances that differ by brand. Height clearance keeps the box off the slide above and lets it tilt in on installation, and the bottom panel is cut slightly smaller than the groove-to-groove distance so it can be slid home. Because every part is derived from the box outside dimensions and the material thickness, one set of numbers produces the whole cut list.

Worked example

For a 450 × 150 mm opening in a 560 mm deep cabinet with side-mount slides and 12.7 mm sides: the box is 424.6 mm wide, 125 mm high and 500 mm deep on 500 mm (20″) slides. Cut two sides at 500 × 125, a front and back at 399 × 125, and a 6 mm bottom of about 410 × 486 mm to sit in a 6 mm-deep groove 10 mm up. An applied front of 447 × 147 mm leaves a 1.5 mm reveal.

Frequently asked questions