You found a great deal on a used LEGO® set. The photos look promising, the price is fair, and the seller swears it's "all there." But is it? "Complete" is one of those words that means something slightly different to everyone. To some sellers it means the big, obvious pieces are present. To a builder, it means every last 1x1 round plate, every minifigure hand, and that one translucent dish that always seems to vanish into the carpet. Below is the way we actually check completeness at CrocoBricks: the same calm, methodical process you can do at your own kitchen table.
The quick checklist (at a glance)
Short on time? Here's the whole process in six steps. The rest of this guide explains each one in detail.
- Find the set number. It's usually printed on the box or the instruction booklet, or you can identify the set from the build.
- Pull the official inventory for that set number from BrickLink or Rebrickable so you have a definitive parts list.
- Sort the loose parts by colour and shape, then count them against the inventory, one element at a time.
- Check the minifigures and accessories separately: heads, hands, hairpieces, capes, weapons and printed parts.
- Look at the small, easy-to-lose pieces last, because they're the ones most likely to be missing.
- Note the box and instructions and decide whether they matter for your purpose (building, collecting or reselling).
That's it. The set is "complete" when every element on the official inventory is physically in front of you. Now let's make each step painless.
Find the official set inventory first
You can't check completeness against a list you don't have. Before you tip a single brick onto the table, get the official inventory for the exact set number. A set number is the four-to-seven digit code (for example, 60271 or 75192) printed on the box and the front of the instruction booklet. If both are missing, you can often identify the set from a distinctive printed piece, a minifigure, or the overall build using an image-recognition tool. Once you have the number, two free resources do all the heavy lifting.
BrickLink inventory
BrickLink hosts a community-maintained catalog of nearly every LEGO® set ever made. Search the set number, open the set page, and click the inventory tab. You'll get a full breakdown of every part: the element, its colour, the official part number, and the exact quantity. BrickLink also separates the regular items from the extras, which matters: those spare 1x1s that LEGO throws in are bonuses, not required pieces, so don't panic if a couple are absent.
Rebrickable
Rebrickable is the other free heavyweight. Its inventories are clean, searchable, and it's particularly good at showing part alternatives: cases where LEGO swapped one mould for an equivalent during a production run. That's useful when a part looks slightly different from the picture but is genuinely the right element. Print the list or keep it open on a tablet and tick each part off as you count, which turns the count into a satisfying checklist rather than a guessing game. Use whichever tool you prefer; many people open both, because between them they cover almost everything.
Check the parts against the inventory
Now the actual work. Pour the loose bricks out onto a light-coloured towel or a baking tray with a rim (the rim stops runaways). Resist the urge to start matching randomly. A little structure here saves a lot of frustration.
Sort by colour and element, then count
Group everything by colour first, then by shape within each colour. Dark bluish gray plates in one pile, red bricks in another, and so on. The official inventory is organised the same way, so once your table mirrors the list, counting becomes mechanical. Work through the inventory top to bottom: find the element, count what you have, tick it off. When a quantity matches, move on without second-guessing. When it doesn't, mark it and keep going. Don't stall on the first gap, because sometimes a piece you thought was missing turns up in a different pile two minutes later.
The easy-to-lose small parts
If a set is going to be incomplete, it's almost always the tiny pieces that are gone. The usual suspects: 1x1 round plates and tiles, transparent studs and jewels, minifigure utensils (cups, frying pans, telescopes), small clips and bars, flick-fire missiles, and the little technic pins that roll off tables. Check these deliberately at the end, when your eyes are tuned in. A handy trick: count the small translucent parts against a window or lamp, because they hide beautifully against a busy background. If you're checking a Technic set, give the pins and axles their own dedicated count: they're the most commonly short.
Verify the minifigures and accessories
Minifigures deserve their own pass, because a "complete" figure is really several parts pretending to be one. A single minifig can include a head, torso, legs, a hairpiece or hat, and accessories like a sword, briefcase or cape. The inventory lists each of these separately, so check them separately. A figure missing its unique printed head or its signature accessory is not complete, even if the body is there, and for collectors, that distinction is the whole ballgame. Pay special attention to printed parts and rare accessories, since those are the pieces sellers most often overlook and buyers most often care about. Capes, cloth elements and tiny weapons are the first things to wander off, so confirm each one against the list rather than trusting a quick glance.
Instructions and the box: do they matter?
This depends entirely on what you want from the set. For pure building, instructions are a nice-to-have rather than a requirement, because the official building instructions for the vast majority of modern sets are available as free PDF downloads from LEGO's own instructions site. Search the set number there and you can print or follow along on a screen, even if the original booklet is long gone. So a set with no paper instructions isn't "incomplete" in any meaningful sense: the parts are what count.
The box is a different story. For builders, the box is irrelevant: it's cardboard. For collectors and resellers, though, an original box (especially undamaged, with sharp corners) can add real value and desirability. If you're buying to build, ignore the box entirely. If you're buying to collect or resell, factor its condition in, but understand that a box has nothing to do with whether the set itself is complete. Completeness is about parts and minifigures; the box and instructions are about presentation and resale.
What to do when parts are missing
So you counted, and a handful of pieces didn't show up. Don't write the set off. Most "incomplete" used sets are missing only a few common elements, and those are usually easy and inexpensive to replace.
The quickest way to fill the gaps is our LEGO® parts finder. Enter the set number and you see every part from that set that we have in stock, with the colour and how many the set needs. Set the quantities to what you are missing and add them to your cart in one go.
Once you've identified exactly which elements are short (and you will know precisely, because you checked against the official inventory), you can order replacement LEGO pieces to fill the gaps. If you're not sure of an element's exact code, our guide on how to find the right part numbers walks you through reading colours and IDs so you order the correct piece the first time.
This is genuinely where a missing-pieces approach turns a "nearly complete" bargain into a finished set. A common rounded slope or a couple of 1x1 plates cost very little to source individually, and suddenly that incomplete eBay or marketplace find is whole again. The trick is precision: order the exact element in the exact colour, which is why doing the inventory check properly pays off twice.
Selling a used set? Grade it honestly
If you're on the other side of the table, the single best thing you can do is describe completeness honestly. "Complete" should mean every element on the official inventory is present, not "complete except for a few small bits." If pieces are missing, say which ones and roughly how many. Buyers respect a clear, honest listing far more than an optimistic one, and you'll get fewer disputes and better reviews for it. State plainly whether minifigures are all present, whether instructions and the box are included, and whether anything is replaced or aftermarket. If you'd rather skip the listing process altogether, our guide on where to sell your used LEGO set covers your options and how to get a fair price. And if you're building out your own collection, you can also browse complete LEGO sets to see how a clearly described, in-stock listing should read.
FAQ
Are stickers required for a set to count as complete?
It depends who's judging. For building, a set is complete with all its bricks and minifigures regardless of stickers; most builders consider stickers optional and many prefer to leave them off. For collectors, unapplied or correctly applied stickers can matter for value, but a missing or applied sticker sheet doesn't make the parts themselves incomplete. When in doubt, just state the sticker situation clearly.
Do I need the original box?
No, not for completeness. The box has no bearing on whether the set's parts and minifigures are all present. It matters for collectors and resale value, but a boxless set with every element is fully complete in the way that counts for building.
How do I check a set without instructions?
Pull the official inventory from BrickLink or Rebrickable using the set number, and download the free instruction PDF from LEGO's official instructions site. Between the inventory list and the PDF, you can verify completeness and build the set without ever needing the original paper booklet.
What if only a few small parts are missing?
That's the most common outcome and the least worrying. Note exactly which elements are short against the inventory, then source them individually. Small common parts are cheap and easy to replace, which turns a "nearly complete" set into a finished one without much fuss. Our parts finder shows which of them we have in stock for your set number.
CrocoBricks is an independent reseller and is not affiliated with the LEGO Group. LEGO® is a trademark of the LEGO Group.
