My son is 9 and slightly ahead of the Lego curve. We have both a large number of freestyle Legos and sets of various sizes. When we open a new set, I always immediately empty all the pieces and sort by color.

With the last set my son opened, the 824-piece Volcano Exploration Base, he poured all the pieces onto a beige surface, one bag at a time, but we did not sort. Some pieces took him a while to find, but overall it took him about the same amount of time with about the same error rate as a set we sorted of equivalent size.

So, my question is, moving forward, as we wind up with larger and larger sets, will his method continue to be about the same efficacy, or will he just get overwhelmed?

What I don't know is if the larger sets also have numbered bags for various portions of the whole such that one could open a few hundred pieces from a single bag which then goes on to make a particular structure.

  • In general terms the time time to find a part goes up with the number of parts. But you also need to find more parts. So the time to assemble a set with N parts is actually (find one part in a pile of N parts) times (find N parts), or N-squared. Keeping N small wins once N gets larger. And there are sets with more than 2000 parts (5000, I think)
    – Móż
    Commented Dec 1, 2016 at 1:40

4 Answers 4


All large sets released in the last few years come in numbered bags. The bags are sorted by logical sections as they appear in the instruction manuals. So for example there will be several bags numbered as #1, several bags numbered as #2, etc.

The intention is that you open all the bags numbered as #1, build that section, then open the bags numbers as #2, etc. This makes building a lot easier, faster, error-free, and a lot less messy.

In very large sets each section usually takes about an hour to build, and the whole set can take 2-5 hours to put together. While some LEGO fans do building marathons and put together sets in one sitting, for most people stretching out the building experience to several days is less stressful and more practical.

Also, note that numbered bags usually allow several people to work simultaneously as, the numbered bags tend to represent chunks of the set that later get assembled. This makes the building process faster. So for example your son would be building the first floor of a structure, while you can work on the second floor.

Another way people work together on large sets is for one person to be the sorter, and the other the assembler. In your case, this may mean that you find the parts for each step of the process, and maybe even build some of the small assemblies, then you hand them to your son who will attach them to the set.

All in all I would say that numbered bags are your friends. The larger the set, the more you will appreciate their practicality. There are still old-school LEGO fans from the pre-sorted bags period, who build differently. They may dump all the pieces from all bags into one pile, or open all the bags and pre-sort pieces by type or color. But for most people, building the way LEGO suggest is the best way to tackle large sets.

  • Even in the numbered bags, as you say, is this amenable to "dump and find" because the piece number is below a few hundred?
    – Stu W
    Commented Nov 18, 2016 at 2:50
  • 1
    Yeah, the piece number in the numbered bags are pretty manageable, even for very large sets, and they are also somewhat pre-sorted. Usually one bag has the really big pieces, another bag would have the tiny pieces, etc. So what I do is to dump the content of the same numbered bags in separate piles. If you have a few trays or other shallow containers, they can be very useful. So for example if you have 3 bags labeled #4, you dump the content of each on a separate tray. Usually there are no more than 3-4 bags under one number, so you will have that many piles. Commented Nov 21, 2016 at 18:43
  • I do the same, but I have a few bowls or varying size to dump the bags into. Sometimes I break out the muffin baking tin for the bags with a lot of small pieces. Then I sort them while my son builds. Often we take turns between pulling the pieces for a step and building that step.
    – VolleyJosh
    Commented Nov 30, 2016 at 17:00

Had an argument with my wife the other day about how to sort. My idea was to do it by colour, but then I realized she was right (obviously) and sorting by type is more practical. Windows and doors go together, thin plates, large plates, wheels, etc.

That said, with the kids we never sort a box just opened. As Mr Shiny and New and Bernd Wilke do, we open the bags by numbers and use plastic containers to avoid losses. Sorting everything first would, in my view, take away a lot of the excitement.

  • A personal preference on my part for color. Really, it's the second time we build something because now we have several hundred unsorted pieces. We're not good at taking apart in order.
    – Stu W
    Commented Nov 28, 2016 at 14:41

For new sets I prefer to open each bag at the time I use it. The bags are small enough to need no further sorting.

In general I like to have my pieces sorted by function and size (no color sorting) as in a pile of red pieces the smaller pieces are more difficult to find than the red pieces in the pile of (equal) small pieces.


I use small square plastic food containers, about 4" sq and 2" deep, one for each plastic bag that comes in the box. If a bag has more bags inside, they each go into a container. If one bag has a lot of large identical pieces, such as doors or door frames, I'll take those out. Otherwise, a bag corresponds to one little tray. If a set has numbered steps, then I only empty the baggies for the current step; the other bags stay sealed until needed.

This gives me a couple advantages:

  1. It's quick.
  2. Each tray is shallow enough to pick parts
  3. The bags in the sets are usually organized so that all or most of a certain kind of piece is in one bag, which makes them easy to find.
  4. Pieces don't fall all over the place or get lost.
  5. If I need to stop, put the build away, then resume later, it's easy to do so.

I think this minimal system is enough to make any kind of pre-sorting unneeded. Rarely has a kit overwhelmed the little boxes (the huge Ghostbusters HQ set did, but it's an outlier).

I also sort my lego before putting a set away. My collection is sorted into flat art-supply boxes, by colour and type. Pre-sorting to that degree takes quite a bit of time. I don't think that time is well-spent when building the set for the first time, even if the sorting wouldn't need to be as thorough for building as it is for storing.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.