Cataloguing a LEGO collection takes about an evening if you record only three things per set: the set number, where it is, and whether it is built. Everything else, name, piece count, year, theme, image and value, can be filled in automatically from the set number, and everything beyond that is optional detail that stalls the job.
Most collections never get catalogued because people start with a spreadsheet column for every possible attribute. Here is a system that finishes.
What to actually record
| Field | Why it earns its place |
|---|---|
| Set number | The key to everything else. 10307, not "Eiffel Tower". |
| Status | Built and displayed, built and stored, sealed, or dismantled. |
| Location | Which shelf, which box, which room. |
| Date acquired | Optional, but it is the field people most regret not having. |
That is it. Piece count, theme, year, RRP and current value all come from the set number. Condition and completeness matter for selling, not for knowing what you own, so add them only if you sell.
Step 1: catalogue before you sort
The instinct is to tidy first and record afterwards. Do the opposite. Cataloguing a shelf takes minutes; reorganising it takes hours, and if you sort first you will lose track of what you have already handled.
Work one shelf or one box at a time, front to back, and do not skip a set because you are unsure of its number. Scan the barcode if the box is still around, otherwise search the set name and confirm by the piece count.
At roughly 20 to 40 sets an hour, a 100 set collection is a single evening.
Step 2: separate the four states
A LEGO collection is not one pile, it is four, and mixing them is what makes collections feel unmanageable:
- Built and displayed. On the shelf, doing its job.
- Built and stored. Assembled but boxed away. This is the category people forget, and the reason for the "do I already own this?" moment in a shop.
- Sealed. Unopened. Track these separately, because they are the ones that quietly accumulate.
- Dismantled. Back to loose parts. Once a set is here, it is a parts donation, not a set.
The single most useful thing a catalogue tells you is not what you own. It is which sealed sets you have not built yet, in order of how long each will take.
Step 3: sort parts by type, then colour
For loose parts, the rule that survives contact with reality is: sort by piece type first, and by colour only within a type.
Colour-first sorting photographs beautifully and slows you down, because when you need a 1x2 plate you have to search every colour bin for the shape. Type-first means you go to the plate drawer and then find the colour.
A workable starting split for a mid-size collection: plates, bricks, tiles, slopes, technic pins and axles, wheels and tyres, minifigures and accessories, and one honest bin for everything else. Refine only when a bin gets annoying to search.
Step 4: decide what to do with the boxes
The recurring argument in every collection. The practical positions:
- Keep boxes only for sets you intend to resell, and flatten them.
- Keep instructions for everything, or note that they are available as free PDFs from LEGO.
- Photograph anything you throw away before you throw it away.
Storage space spent on boxes is storage space not spent on sets.
Step 5: keep it current in under a minute
A catalogue decays the moment it becomes a chore. The maintenance rule is simple: record a set at the moment it enters or changes state, not in a monthly session.
New set home from the shop: scan it in as sealed. Start building it: mark it built. That is 20 seconds each, and it is the difference between a catalogue you trust and a spreadsheet you stopped updating in March.
This is where an app genuinely beats a spreadsheet, and we wrote about that trade-off honestly in spreadsheet vs app. A spreadsheet needs manual entry for every field; an app fills them from the set number and lives in your pocket at the moment you need it.
Which tool for which job
| Tool | Best at |
|---|---|
| Brickset | Set data, specs and community reviews |
| Rebrickable | Parts inventory and what you can build from them |
| BrickEconomy | What the collection is worth |
| SetSquad | What you own, what you have built, and how long each build took |
Most collectors use more than one, and they are all free. If you want the cataloguing and the building record in the same place, SetSquad scans sets into your collection and times the builds, on iOS and Android.
And once the catalogue exists, a genuinely useful thing becomes possible: sorting your unbuilt sets by how long each one takes, so you can pick a build that fits the evening you actually have.