What IKEA publishes, and what it leaves out
IKEA product pages give outside dimensions and load limits. They do not give the inside size of a cube or shelf. The 2x2 KALLAX shelf unit is listed at 30 1/8 in wide, 15 3/8 in deep and 30 1/8 in high, with a 29 lb maximum load per shelf and 55 lb on the top. [1] The 2x4 unit is 30 1/8 in wide, 15 3/8 in deep and 57 5/8 in high, with the same 29 lb shelf limit. [2]
The closest IKEA figure for the inside of a KALLAX cube is its own insert. The KALLAX insert with 2 drawers is listed at 13 in wide, 13 in high and 14 5/8 in deep, and IKEA says it is "dimensioned to fit KALLAX shelf unit". [3] This guide uses 13 x 13 x 14 5/8 in (about 33 x 33 x 37 cm) as the usable cube.
The 31 1/2 in BILLY bookcase is 31 1/2 in wide, 11 in deep and 79 1/2 in high. It comes with one fixed shelf and four adjustable shelves, each rated to 66 lb. [4] Because the shelves move, the height between them is up to you. The width and depth inside are a little smaller than the outside figures, by an amount IKEA does not publish.
When we searched IKEA's US store for DETOLF on 30 October 2026, no DETOLF product came up. The results showed other glass-door cabinets, led by BLÅLIDEN. [6] The BLÅLIDEN glass-door cabinet is 13 3/4 in wide, 12 5/8 in deep and 59 1/2 in high, but each shelf is rated to only 7 lb. [5] We use it below as the narrow glass-cabinet option.
| Furniture (IKEA US, 30 Oct 2026) | Outside W x D x H | Space used here | Load limit | Price |
|---|---|---|---|---|
| KALLAX 2x2 shelf unit | 30 1/8 x 15 3/8 x 30 1/8 in | Cube about 33 x 33 x 37 cm (insert size); top 76.5 x 39 cm | 29 lb per shelf; 55 lb on top | $49.99 [1] |
| KALLAX 2x4 shelf unit | 30 1/8 x 15 3/8 x 57 5/8 in | Same cube size | 29 lb per shelf | $79.99 [2] |
| BILLY bookcase | 31 1/2 x 11 x 79 1/2 in | Outside width 80 cm, depth 28 cm; shelf height adjustable | 66 lb per shelf | $79 [4] |
| BLÅLIDEN glass-door cabinet | 13 3/4 x 12 5/8 x 59 1/2 in | Outside width 35 cm, depth 32 cm | 7 lb per shelf | $139.99 [5] |
Eight popular sets against the shelves
Set sizes are Brickset's listed model sizes. [7]-[14] Brickset gives three figures without labelling them. This guide reads them as height, width and depth for the buildings, and takes the first figure as the length for Titanic and Concorde. Check the box or LEGO's own product page if a single centimetre decides the fit. "Fits" means the model is smaller than the space on all three sides. "Tight" means less than about 2 cm is left on one side, which is too little to route a light kit lead without pinching it.
A wide set can sometimes fit a cube turned sideways. Hogwarts Castle and Grounds is 35 cm wide and 25 cm deep. Facing forward it is 2 cm too wide for the 33 cm cube. Turned so the 35 cm side runs front to back, it fits within the 37 cm insert depth with about 2 cm to spare. [9][3] The catch is that you then see the model side-on.
| Set (listed size) | KALLAX cube 33 x 33 x 37 cm | Top of KALLAX 2x2 (76.5 x 39 cm) | BILLY shelf (80 x 28 cm outside) | BLÅLIDEN shelf (35 x 32 cm outside, 7 lb) |
|---|---|---|---|---|
| Bonsai Tree 10281: 18 H x 21 W x 20 D cm [10] | Fits, with 15 cm headroom | Fits | Fits | Fits outside dimensions |
| Alpine Lodge 10325: 21 H x 24 W x 16 D cm [11] | Fits | Fits | Fits | Fits outside dimensions |
| Tudor Corner 10350: 31 H x 26 W x 25 D cm [7] | Fits, with 2 cm headroom | Fits | Fits; 3 cm under outside depth | Fits outside dimensions; check inside |
| Hogwarts Castle and Grounds 76419: 21 H x 35 W x 25 D cm [9] | Only turned sideways; tight | Fits | Fits | No: too wide facing forward, too deep turned |
| Natural History Museum 10326: 31 H x 39 W x 25 D cm [8] | No: 6 cm too wide | Fits | Fits; 3 cm under outside depth | No: too wide |
| Rivendell 10316: 39 H x 75 W x 50 D cm [13] | No | No: 11 cm overhang at the front or back | No: too deep | No |
| Concorde 10318: 105 L x 15 H x 43 wingspan cm [14] | No | No: longer than the top | No: longer than the shelf | No |
| Titanic 10294: 135 L x 44 H x 16 W cm [12] | No | No | No: 55 cm longer than the shelf | No |
Adding a case: Lightailing case sizes against the shelves
Lightailing lists its dust-cover cases and front-opening cases by size in centimetres. The 2-pack dust-cover cases include 25 x 25 x 25 cm at $32.99, 25 x 25 x 35 cm at $33.99 and 36 x 27 x 27 cm at $34.99. [15][19][16] Its single BRIKSMAX front-opening cases include 19 x 19 x 32 cm at $43.99 and a lighted 19 x 19 x 24 cm model at $44.99. [17][18] The listings give these sizes without saying whether they are outside or inside measurements, so allow for wall thickness when you fit a model into one.
Inside a KALLAX cube, how the case opens matters as much as its size. A lift-off dust cover needs room above the case to lift clear. A 25 cm cover in a 33 cm cube has about 8 cm to lift, so you would slide the whole case out to open it. A front-opening case can be opened where it sits.
| Lightailing case (listed size) | KALLAX cube 33 x 33 x 37 cm | BILLY (28 cm outside depth) | Holds (by listed size) |
|---|---|---|---|
| Dust cover 25 x 25 x 25 cm, $32.99 2-pack [15] | Fits; slide out to lift the cover | Fits; three side by side use 75 of 80 cm outside width | Bonsai Tree, Alpine Lodge (not Tudor Corner: 31 cm tall) |
| Dust cover 25 x 25 x 35 cm, $33.99 2-pack [19] | No: 35 cm is taller than the cube | Fits if the shelf is set high enough | Bonsai Tree or Alpine Lodge (not Tudor Corner: 26 cm wide) |
| Dust cover 36 x 27 x 27 cm, $34.99 2-pack [16] | Only with the 36 cm side running front to back; about 1 cm spare, no lead room | No: 27 cm and 36 cm sides both near or over the depth | Alpine Lodge (24 W x 16 D x 21 H), Bonsai Tree, or Hogwarts Castle and Grounds (35 W x 25 D x 21 H) with about 1 cm to spare |
| Front-opening 19 x 19 x 32 cm, $43.99 [17] | Fits; about 1 cm headroom | Fits | Narrow tall models under 19 cm square |
| Lighted front-opening 19 x 19 x 24 cm, $44.99 [18] | Fits; room behind for its lead | Fits | Small models under 19 cm square |
Weight and power: the two checks after size
Weight decides more than size for the glass cabinet. BLÅLIDEN's 7 lb (about 3.2 kg) per-shelf limit is far below KALLAX's 29 lb and BILLY's 66 lb. [5][1][4] IKEA's pages do not list set weights. Brickset lists a boxed weight for some sets, not the weight of the built model: 3.55 kg (7.83 lb) for Tudor Corner and 5.14 kg (11.33 lb) for Natural History Museum. [7][8] The built model weighs less than the full box, but those figures are already above BLÅLIDEN's 7 lb shelf rating, so weigh the built set on a kitchen or luggage scale before you put it on a BLÅLIDEN shelf.
All four IKEA pages carry the same warning: the furniture must be anchored to the wall to prevent tipping, with screws and plugs suited to your wall. [1][2][4][5] The BILLY page adds that the brackets are included, but the screws or fixings for the wall are sold separately. [4]
A lit set needs a path for its lead. Leave at least 2 cm free somewhere, usually behind the model. Check whether the lead has to pass the back panel or a glass door before you settle on a shelf. Our wall-mounting and case guides go through cable exits in detail.
- Measure the real inside of your shelf. IKEA's published sizes are outside sizes, except for the insert used here as a guide.
- Write down your set's height, width and depth from Brickset or the box, and note which figure is the length.
- Try the model turned sideways if it is too wide facing forward.
- Leave room above a lift-off case cover, or choose a front-opening case.
- Check the per-shelf load limit against the weight of the set plus its case.
- Plan where the light kit lead and the USB plug or battery box will sit.
Who this pairing table helps, and who should measure instead
The table is most useful for modular-sized and small display sets, where a few centimetres decide whether a set goes in a cube or on top. Owners of long ships, aircraft and large castles will find none of these shelves fits. They need a dedicated wall frame or a deeper cabinet, both covered in our display frame size guide.
IKEA's current US KALLAX listing says 30 1/8 in wide. [1] If your unit is an older one, measure it rather than assume it matches.
Questions before you decide
What size LEGO set fits in a KALLAX cube?
IKEA's KALLAX insert, which it says is dimensioned to fit the shelf unit, measures 13 x 13 x 14 5/8 in (about 33 x 33 x 37 cm). By Brickset's listed sizes, Bonsai Tree 10281, Alpine Lodge 10325 and Tudor Corner 10350 fit inside. Tudor Corner has only about 2 cm of headroom.
Does a modular building fit on a BILLY bookcase?
By outside size, yes for depth. BILLY is 11 in (about 28 cm) deep, and Tudor Corner and Natural History Museum are listed at 25 cm deep. That leaves about 3 cm before panel thickness, so measure inside the shelf first.
Is the IKEA DETOLF still sold?
A search of IKEA's US store for DETOLF on 30 October 2026 returned no DETOLF product. The results led with the BLÅLIDEN glass-door cabinet, listed at 13 3/4 x 12 5/8 x 59 1/2 in with a 7 lb per-shelf limit.
Where can a large set such as Rivendell or Titanic go?
Not on these shelves. Rivendell is listed at 50 cm deep, against 39 cm for KALLAX and 28 cm for BILLY. Titanic is 135 cm long, against 80 cm for BILLY's outside width.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- IKEA US: KALLAX shelf unit, white, 30 1/8x30 1/8 in Accessed 30 Oct 2026
- IKEA US: KALLAX shelf unit, white, 30 1/8x57 5/8 in Accessed 30 Oct 2026
- IKEA US: KALLAX insert with 2 drawers, 13x13 in Accessed 30 Oct 2026
- IKEA US: BILLY bookcase, white, 31 1/2x11x79 1/2 in Accessed 30 Oct 2026
- IKEA US: BLÅLIDEN glass-door cabinet, black Accessed 30 Oct 2026
- IKEA US store search results for "detolf" Accessed 30 Oct 2026
- Brickset: 10350 Tudor Corner Accessed 30 Oct 2026
- Brickset: 10326 Natural History Museum Accessed 30 Oct 2026
- Brickset: 76419 Hogwarts Castle and Grounds Accessed 30 Oct 2026
- Brickset: 10281 Bonsai Tree Accessed 30 Oct 2026
- Brickset: 10325 Alpine Lodge Accessed 30 Oct 2026
- Brickset: 10294 Titanic Accessed 30 Oct 2026
- Brickset: 10316 The Lord of the Rings: Rivendell Accessed 30 Oct 2026
- Brickset: 10318 Concorde Accessed 30 Oct 2026
- Lightailing display case with dust cover, 25 x 25 x 25 cm (2 pack) Accessed 30 Oct 2026
- Lightailing display case with dust cover, 36 x 27 x 27 cm (2 pack) Accessed 30 Oct 2026
- Lightailing BRIKSMAX front-opening display case, 19 x 19 x 32 cm Accessed 30 Oct 2026
- Lightailing lighted front-opening display case, 19 x 19 x 24 cm Accessed 30 Oct 2026
- Lightailing display case with dust cover, 25 x 25 x 35 cm (2 pack) Accessed 30 Oct 2026
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