The arithmetic is simple — divide by 42 and round down — but the interesting part is what happens to the remainder, because that's what decides whether the result feels deliberate or improvised.
cells = floor( drawer size ÷ 42 )
Metric drawers
Measured internally, at the tightest point, after subtracting 1–2 mm of slack:
| Drawer | Cells | Grid | Left over |
|---|---|---|---|
| 200 mm | 4 | 168 mm | 32 mm |
| 250 mm | 5 | 210 mm | 40 mm |
| 300 mm | 7 | 294 mm | 6 mm |
| 350 mm | 8 | 336 mm | 14 mm |
| 380 mm | 9 | 378 mm | 2 mm |
| 400 mm | 9 | 378 mm | 22 mm |
| 450 mm | 10 | 420 mm | 30 mm |
| 500 mm | 11 | 462 mm | 38 mm |
| 550 mm | 13 | 546 mm | 4 mm |
| 600 mm | 14 | 588 mm | 12 mm |
| 700 mm | 16 | 672 mm | 28 mm |
| 800 mm | 19 | 798 mm | 2 mm |
Notice how uneven the remainder is. 380 mm and 800 mm land within 2 mm of a whole grid; 250 mm and 500 mm waste nearly a full cell. That's worth knowing before you buy furniture, and worth checking against both axes — a drawer can be generous one way and awkward the other.
Inch drawers
The grid is metric, so imperial drawers rarely land neatly. Convert once and work in millimetres from there:
| Drawer | Millimetres | Cells | Left over |
|---|---|---|---|
| 12" | 304.8 mm | 7 | 10.8 mm |
| 15" | 381.0 mm | 9 | 3.0 mm |
| 16" | 406.4 mm | 9 | 28.4 mm |
| 18" | 457.2 mm | 10 | 37.2 mm |
| 20" | 508.0 mm | 12 | 4.0 mm |
| 22" | 558.8 mm | 13 | 12.8 mm |
| 24" | 609.6 mm | 14 | 21.6 mm |
15" and 20" are unusually kind. 18" is the worst on this list — 37 mm short of another cell, which is nearly a whole wasted column.
What to do with the remainder
Every drawer has some. Three approaches, and the right one depends on how much:
- Under about 15 mm — make it a solid margin around the grid. The plate fills the drawer, can't shift, and the border strengthens the edge.
- 15 to 30 mm — push it to one side rather than splitting it. A single 25 mm strip at the back is usable space for long thin things; two 12 mm strips are usable for nothing.
- Over 30 mm — re-measure first, because you may be one cell off. If it's real, and often it is, consider whether a strip that wide would be better as a separate compartment than as baseplate margin.
Margins can be set per side, so the grid doesn't have to sit centred. Pushing it to the back and keeping the slack at the front, where you reach in, is usually the more useful arrangement.
Don't forget the height
Width and depth decide the grid; height decides whether anything you put in it actually closes. Three things stack up:
4.25 (baseplate) + 7 × units + 4 (top lip) ≤ usable height
Measure from the drawer floor to whatever is above it — the underside of the worktop, a rail, or the drawer above. An 84 mm drawer gives 79.75 mm above the plate, which is ten 7 mm units in total: one deep layer, or two layers of five.
Bin heights are quantised, and the 7 mm includes the bin's own base — see bin heights in the main guide for what that leaves you inside.
Common questions
My drawer is 250 mm and wastes 40 mm. Can I do better?
Not within the standard grid — 42 mm is fixed, and six cells needs 252 mm. Put the 40 mm somewhere useful rather than spreading it: a single strip that wide holds pens, files or long tools perfectly well.
Should I measure the drawer or the opening?
The drawer, internally, at its tightest point. The opening is usually larger and will give you a plate that doesn't fit.
What if the drawer isn't square?
Use the smallest measurement on each axis. A plate sized to the widest point will jam.
Do the cells have to fill the whole drawer?
No. A grid covering two thirds of a deep drawer, with the back left open for tall items, is a perfectly good design and uses far less filament.
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