My son has thousands of pieces of LEGO, but he has them all dumped in a box. Is there any way to figure out what sets they went to if I don't remember the names of them?


First thing to do would be to get together any building instructions you have and attempt to build those sets one at a time noting any missing elements as you go.

Once this is complete and if you still have unsorted pieces, you could use a website such as Bricklink.com to try to identify the sets and then use Peeron.com to source the building instructions for that set.

To begin this process, try to select an odd looking piece that is uncommon in your collection. Use Bricklink to try to identify the piece and then click through to the catalog entry for that piece to see the list of sets that piece is included in. You can follow the links to get an inventory of the selected set and then see how many of the required pieces you have in the unsorted box.

This is not an exact science and will require a fair amount of trial-and-error, not to mention time, but these two websites are two of the best LEGO resources available for such a task.

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  • In addition of odd-looking pieces, you may want to have a look at the minifigs, too. Some of them are unique to some sets, which should help a lot, but trying to identify them might be a pain. – Joubarc Oct 18 '12 at 4:04

Before you start:

  • It can be a big help to sort the parts, at least in some rudimentary way. Sorting by colour is least helpful, by shape much better.

  • Don't dismantle partial assemblies until you've either (a) identified the sets that they come from or (b) you're sure they won't help you identify particular sets.

To help you identify the sets:

  • Search through anything that you've got that is made of paper - sticker sheets, instructions, boxes or bits of boxes, etc. These often have set numbers on them, or pictures from which you can identify sets.
  • If you find a part with a number printed / stickered on to it, that number could well be a set number.
  • Find other bricks with stickers or designs. These can be a good indication of the kind of sets they are from.
  • Look for other unusual parts or parts in unusual colours. Minifigs and their accessories are a good starting point.
  • Look for partially completed models that look like they come from sets. It is usually easy to tell the difference between something that a child's build from something that was designed by LEGO.
  • Look at the general mix of parts. Lots of bricks that are 2 studs wide suggests that they come from basic building sets, whereas 1-stud wide parts are more likely to be walls for buildings. Lots of grey could indicate Star Wars sets. It is fairly easy to identify Bionicle and Technic parts.
  • Most collections of LEGO span a decade or so, so you can limit the identification process to the if you can guess the era covered by the collection - either from your child's age, from any sets you can identify, or from individual parts that were only made for a short time. Remember, however, that this is not a hard-and-fast rule - many collections have sets / bricks from outside their core collecting years.
  • Bare in mind that LEGO often produce several quite similar sets. For example, if you think you're fairly sure you've got a fire engine but can't find half the parts you expect, then you're probably trying to find the parts from the wrong fire engine.

Get to know the following reference sites:

If all else fails, post pictures of the less common parts here and we'll see if we can help identify the sets that they're from.


  • Don't despair if you can't sort everything out. LEGO is about creativity, not just the sample designs that LEGO supply!
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Here's what I did after finding a couple of old LEGO boxes stashed away in my parents' house.

  1. Create a user and log into Rebrickable.com.
  2. Under 'My Parts', create a new part list, and start adding your parts using their catalog. They have a very good search engine and you can quickly find most, if not all, of the exact parts.
  3. Once done, go to the 'Build' section, where you can see which LEGO sets you can build from your part list. It gives you a percentage so e.g. if you have a set with 91% match, then that's probably the original set, and you're just missing a few odd parts.

I did all that (took a while, had over 800 pieces to catalog....), figured out which sets are the most probable ones, and ordered the missing parts (usually from BrickLink.com) to complete them.

It was really an excitement to see some 30-year old lego sets being built again :)

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  • Exactly what I was looking for, cheers – Henrique de Sousa Nov 13 '19 at 14:59
  • Gonna try this NOW! – warhansen May 7 at 12:48

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