What length drawer slides fit a 24 in deep cabinet?

A 24 in (610 mm) deep cabinet takes a 22 in (559 mm) side-mount slide or a 21 in (533 mm) undermount slide. The forum threads on this question split between those two numbers, and both camps are right for the slide they own: side-mount ball-bearing slides are sold in 2 in steps, undermount runners in 3 in steps, and 22 in and 21 in are the longest of each that fit inside the box. What a one-line answer leaves out is the drawer box each slide carries, and how much of the drawer is left to store things in. That is what this page adds, for base, vanity and wall carcasses, framed and frameless.

The 24 in is measured over the back panel, not inside it#

A 24 in base cabinet is 24 in from the front edge of the carcass to the back face of its back panel. The door or drawer front sits in front of that, and the worktop overhangs further, which is why a kitchen run finishes at about 25 in (64 cm) at the counter edge, as counter and cabinet heights sets out. A slide does not care about any of that. It cares about the inside depth: the distance from the face the slide starts at to the inside face of the back.

That face differs between the two ways cabinets are built.

• Frameless. The slide starts at the front edge of the carcass side. Inside depth is the carcass depth minus the back. With a 3/4 in (19 mm) back, a 24 in box has 23 1/4 in (591 mm) inside.
• Face frame. The slide starts behind a 3/4 in (19 mm) frame glued to the front. Inside depth is the carcass depth minus the frame and the back, so a 24 in box has 22 1/2 in (572 mm).

The figures on this page assume a 3/4 in back, or a thinner back set in a groove with the same 3/4 in lost behind it. A 1/4 in (6 mm) back fixed flat to the rear edges gives 1/2 in (13 mm) more, and the measuring method that settles which you have is the one in how we measure: tape from the face the slide starts at, to the back, at the height the slide will sit.

24 in, 21 in and 12 in carcasses, every slide that fits#

The rules that decide each row are short. Accuride's 3832, the standard side-mount ball-bearing slide, is 12.7 mm (1/2 in) thick and Eagle Woodworking's listing for the 3832EC says the slide "should be equal in length to your drawer box depth"; it is sold in 2 in steps from 14 to 28 in. Blum's catalogue gives its MOVENTO and TANDEM undermount runners a space requirement in the cabinet of the nominal length plus 3 mm, and a drawer length of the nominal length minus 10 mm. In the US Blum sells MOVENTO from 12 to 30 in and TANDEM from 9 to 21 in, both in 3 in steps.

The usable depth assumes a 1/2 in (12.7 mm) front and back on a side-mount box and 5/8 in (16 mm) on an undermount box, the thickest side Blum's catalogue allows for MOVENTO.

The 12 in rows use the 250 mm 3832, since the inch listing starts at 14 in. In the 24 in rows the face frame changes nothing; in the 21 in rows it takes the side-mount from 20 in down to 18 in.

Why the next size up never fits: 24 in needs 613 mm#

Undermount, 24 in base, frameless. Inside depth 610 - 19 = 591 mm. A 21 in runner is 533 mm and needs 533 + 3 = 536 mm, which leaves 55 mm (2 1/8 in) to spare. The next size, 24 in, is 610 mm and needs 613 mm, 22 mm (7/8 in) more than the box has. Behind a face frame, 572 mm against the same 536 and 613 mm: the answer is unchanged.

Side-mount, 24 in base, frameless. A 22 in slide is 559 mm against 591 mm inside, 32 mm (1 1/4 in) spare. The next size, 24 in, is 610 mm, 19 mm longer than the inside depth before any clearance at all. Behind a face frame 22 in still fits, with 13 mm (1/2 in) to spare.

Undermount, 21 in vanity, frameless. Inside 533 - 19 = 514 mm. A 21 in runner needs 536 mm, 22 mm too many, so the runner drops a whole 3 in step to 18 in (457 mm, needing 460 mm). That is the largest single loss on this page: 3 in of slide given up for 7/8 in of shortfall. A side-mount, in its 2 in steps, drops only to 20 in, which fits 514 mm with 6 mm (1/4 in) to spare.

Undermount, 12 in wall cabinet. Inside 305 - 19 = 286 mm. A 12 in runner (305 mm) needs 308 mm, so the cabinet takes a 9 in (229 mm) TANDEM. MOVENTO starts at 12 in in Blum's US range and does not fit a 12 in carcass at all.

22 in or 21 in: why the forum answers disagree#

The disagreement in the search results is not a disagreement about cabinets. 22 in is a side-mount size: side-mount slides are sold in 2 in steps (14, 16, 18, 20, 22, 24 in for the 3832EC). 21 in is an undermount size: Blum sells its runners in 3 in steps (9, 12, 15, 18, 21, 24 in). Neither range contains the other's number, so an answer of 22 in and an answer of 21 in are each the longest slide in one catalogue below 23 1/4 in, and each is correct for that catalogue. The question as typed never says which slide, and that is the whole argument.

The third answer, 24 in, is wrong for any cabinet built to a 24 in carcass depth, for the reason in the first section: the 24 in includes the back. A tape run from the face of the drawer front to the wall reads more than 24 in, and the slide never sees any of that extra depth.

What the box gives back: 21 in of storage against 19 5/16 in#

The width rule is the one that ruins a box. For a side-mount the box is the opening minus 1 in (25 mm). For a Blum undermount it is the inside width minus 42 mm, tolerance +0.0 / -1.5 mm, so never wider than the rule. Convert with the unit converter rather than by eye; the traps are in imperial versus metric.

The drawer side has to be tall enough, and thin enough#

Side-mounts set a minimum height. Accuride's 3832 is 45.7 mm (1.8 in) tall, so the drawer side has to be at least that tall to carry it. Very shallow drawers, the kind in a desk or under a changing table top, are the ones to check against that figure before the slide is bought.

Undermounts set a maximum thickness. Blum's catalogue gives 12 to 15 mm sides for MOVENTO, with 16 mm as the limit that still allows side adjustment, and 11 to 16 mm for TANDEM. A 3/4 in (19 mm) solid side, common in hand-built boxes, is too thick for either. Side-mounts take any side thickness, since the slide bolts to its face.

Accuride's load figure is for "a pair of side mounted slides installed 450mm apart", about 17 3/4 in, so a much wider drawer of tools under a workbench is outside the rating.

Where these numbers stop applying#

Runner-specific data sheets. The NL + 3 mm rule is from Blum's European catalogue pages for the 760H, 766H and 560H runners. Blum's product data for the 769R5330S, a MOVENTO with BLUMOTION S runner at 533 mm, lists a minimum internal cabinet depth of 590 mm, not 536 mm. That still fits a 24 in frameless base, by 1 mm, and does not fit behind a face frame, at 572 mm. Read the sheet for the exact runner before building the cabinet around it.

Backs and nailers. A 1/4 in back fixed to the rear edges adds 1/2 in (13 mm) to every inside depth above. That changes no slide in the table: the closest case, the 21 in face frame vanity, reaches 508 mm, exactly the length of a 20 in side-mount with nothing to spare. A trap or pipe chase behind a sink drawer in a bathroom vanity takes depth away again.

Metric runners. Blum's metric 760H steps from 250 to 600 mm in 20 to 50 mm jumps, so the 3 in drop that costs the 21 in vanity its slide does not happen; see drawer runner in the glossary.

Wall cabinets. Most upper cabinets are 12 in deep and have no drawers; a 12 in carcass on a counter, or a 12 in laundry cabinet, takes a 9 in undermount and a box with 7 3/8 in (187 mm) inside.

Open drawers need 22 in of floor before anyone stands there#

A full-extension slide brings the whole box out: Accuride's 3832 is rated at 100 per cent extension, so a 22 in drawer projects 22 in (559 mm) plus its front into the room. Add a person bending to look in and you need the 40 to 44 in (102 to 112 cm) of clear floor the storage hub gives in front of a drawer. In a kitchen that is the aisle: island clearances starts at 42 in (107 cm) for a work aisle, against 36 in (91 cm) in walkway widths where nothing opens.

A built-in drawer bank in a wardrobe is laid out with the wardrobe and closet planner, the shelves above it in shelf span and sag, and the sources behind every figure are on standards and codes.