Writing a LEGO® set list when you do not know the set numbers

Every LEGO® set has a number, it is printed on the front of the box, and it is the single most useful thing you can give anybody who is going to put a price on your collection. A list of set numbers and quantities is a valuation waiting to happen. A list of descriptions is a guessing game. This guide shows you where the number is, what to do when it has worn off or the box is gone, and how little detail is actually enough, so that you can write a usable list in an evening rather than a week.

It is written for people selling a collection, especially one they did not build themselves, and it assumes no knowledge of LEGO beyond being able to read a box.

Why does the set number matter so much?

Because it is the only thing that pins down exactly what a box is. "A big Star Wars ship" could be any of dozens of sets across twenty years, with prices that differ enormously. "75192" is one set, made in one period, with a known piece count, a known retirement date and a public record of what sealed copies have recently sold for. The number turns a description into a fact.

It also saves everybody time. A specialist with a list of numbers can price a large collection in a few hours. The same specialist with a list of descriptions has to work out what each line is before they can start, and they will price cautiously wherever they are not sure, which is not in your interest.

Where is the number on the box?

In three places on almost every modern box.

1. The front of the box

Look at the front, the side with the big picture of the built model. The set number is printed in a clear box or on its own, usually in one of the bottom corners, sometimes along the bottom edge. It is four, five, six or occasionally seven digits with no letters. Next to it there is normally an age guide, and often the piece count.

2. The instruction booklet

If the box has been opened, the instruction booklet has the same number on its front cover, usually in the same place. For a set with several booklets, each carries the number.

3. The barcode panel

On the bottom or the back of the box, next to the barcode, the number appears again in small print, often alongside other codes. This is the copy that survives when the front has faded, because it is on a face that was rarely in the light.

Older sets, from the 1990s and earlier, follow the same idea with different packaging: the number is still on the front, usually smaller, and sometimes on the lid of a box that opens like a tray. Very old sets may have three or four digit numbers.

What do the numbers mean?

Nothing you need to decode, but knowing the rough patterns helps you spot a number when a box is cluttered with other figures, and it helps you notice when something you have written down cannot be right.

These are patterns, not rules. Themes change prefixes over the years and there are exceptions everywhere. The point is only that if you have written down "42110" for a Star Wars set, something has gone wrong, and if you have written "1969" you have probably copied a year or a piece count rather than a set number.

What if the number has worn off or the box is damaged?

Work down this list until one of them gives you an answer.

1. Check the other places. The barcode panel on the bottom or back of the box is usually intact even when the front is faded. The instruction booklet, if the set is opened, has it too.
2. Use the barcode. The thirteen digit number under the barcode identifies the set as reliably as the set number, and it can be searched on the same sites that list LEGO sets. Write it down in full if the set number is unreadable.
3. Use the name. Most boxes carry the set's name on the front. A search for the name together with the word LEGO on any of the public LEGO catalogue sites will show you the set and its number. If several sets share a name, the picture on the box tells you which.
4. Photograph the front. A clear photograph of the front of the box, taken square on in good light, is enough for anyone who deals with LEGO regularly to identify the set. It is also enough for a first conversation with a buyer.
5. Describe it properly if all else fails: the theme, what the model is, roughly how big the box is, and any year printed anywhere on it. That narrows it down enough that the number can usually be worked out at the other end.

What not to do: do not open a sealed box to find the number on the instructions. Everything you need is on the outside, and opening the box moves the set into a different market with a lower price. The guide on sealed, opened and loose LEGO explains why that matters.

How do you use the barcode instead?

Every LEGO box sold in the UK carries a standard retail barcode, the same kind as on a tin of beans, and the thirteen digit number printed under it identifies the set as precisely as the set number does. Boxes from LEGO's own European supply usually carry a number beginning 5702, and boxes packed for the American market usually begin 673419. Both are LEGO. Either one, typed into a search engine together with the word LEGO, or into any of the public LEGO catalogue sites, will return the set.

The barcode is useful in three situations:

• The front of the box is faded or damaged but the bottom or back is intact, which is common on sets that spent years on a shelf with the front facing the window.
• You are listing quickly with a phone. Most phone cameras will read a barcode, and a barcode scanning app that shows the number saves typing. Copy the number into your list next to the box.
• You want a buyer to be certain which version of a set you have. A few sets were released in more than one version over the years, and the barcode settles it where the set number alone does not.

If you are sending a list to a buyer and only have barcodes for some boxes, that is fine. Put the barcode in the number column and say so. Anyone who deals with LEGO regularly can turn a barcode into a set in seconds.

What if there is no box at all?

Then you are describing an opened set or loose bricks, and the number is still worth finding if you can.

• Instructions. If the booklet survived, the number is on its cover. That is enough to identify the set even without the box.
• The built model. A photograph of the assembled model, or of the distinctive parts if it has been taken apart, will identify most sets to anyone who knows the range.
• Minifigures. Figures are often unique to one or two sets, and a photograph of them narrows things down quickly.
• Loose bricks in a tub do not need a set number. They are sold by weight, and the useful information is the weight and whether there are figures mixed in.

How much detail is actually enough?

Less than most people think. A usable list has three columns:

1. Set number. Or the barcode, or the name, in that order of preference.
2. Quantity. How many of that set. Three copies of one set is a different thing from three different sets, and it should be written as one line with a quantity of three rather than three lines.
3. Condition, in one word. Sealed, opened, or loose. If a sealed box has obvious damage, add one more word: crushed, faded, damp. That is all.

Everything else is optional. You do not need the name if you have the number. You do not need the piece count, the year, the theme, what you paid for it, or where you bought it. You do not need to look up a price yourself, although the guide on how a LEGO collection is valued shows you how if you want a rough idea before any conversation.

A phone note is fine. A spreadsheet is fine. A photograph of a handwritten list is fine. What matters is that every box is on it once, with a number and a quantity.

A quick way to list a large collection

For a collection of a hundred boxes this is an evening. For a few hundred it is a weekend. It is the single most valuable weekend you will spend on the collection, because it is what turns a stack of cardboard into something that can be priced.

Common questions

No. The number is enough on its own. Names help only when a number is missing.

It is a very good start. Check it against the shelves, because collections change after the last time a list was updated, and add a condition column if it does not have one.

For a first conversation, yes. For a firm figure, a buyer will still need a list, and they will either ask you for one or build it themselves from your photographs, which takes longer and prices more cautiously.

The shorter one, usually four or five digits, in the most prominent position. The other is often the piece count or a product code for a multipack.

Almost certainly not. Seven digit codes starting with 6 are usually product codes for the box or packaging. The set number will be elsewhere on the front, shorter, and more prominent.

Polybags carry their number on the bag itself, usually on the front near the LEGO logo, and they are listed the same way as boxes. They are often five digits starting with 30 or 40.

No. A clear photograph of a handwritten list works. What matters is that every box is on it with a number and a quantity.

Usually, yes. LEGO sometimes refreshes box art part way through a set's life without changing the number. Write the number once with the total quantity, and mention the two designs in a note if you like. A buyer may ask which is which, but it rarely changes the price.

Promotional sets and gifts with purchase have their own numbers, printed on the bag or box like any other set, often five digits starting with 40 or seven digits starting with 5000. List them the same way. Some are worth more than the set they came with.

Written by Peter Pilling, BuyMyBricks, 10 September 2026. LEGO® is a trademark of the LEGO Group, which does not sponsor, authorise or endorse this site. The number patterns described are general and have exceptions; the number printed on your own box is always the one that counts.