Understanding LEGO part numbers (2024)

From the outside we can only guess what is going on at LEGO HQ, but very interesting to see that there has been an attempt at a cohesive design+color scheme, at least early on.

As a data guy this article sums up a lot of what I have pieced together and draws some connections I hadn't made yet, and the timeframes are always nice to know.

As a database that actually tracks all of these details, Brickset is in the perfect position to bring a dose of insight to this side of the hobby, thank you for the effort and dedication to doing things by the book.

--Nathan

Excellent article and very helpful, thanks

@Librarian1976 said:
"What about a non-identical element that is a slight variation on the underside. For example, a 1x2 jumper with bottom type A vs. bottom type B vs. bottom type C?"

This is a good example because there is a functional difference between B and C, and type A doesn't have the helpful little groove. In this case it could be important that the correct variation is used or things will not work out during the build process.

Alternatively, other differences are more structural. For people that want to part out a 100% authentic Cafe Corner, it will be necessary to track down 1x2x3 wall panel 2362b in white (20 are needed). This specific variant has skyrocketed in price on Bricklink, but the current version with reinforced sides is not overly expensive, having appeared in 62 sets to date. I think it comes down to how much you are willing to pay to have the correct elements, even if it's not explicitly needed for the model. And How much will that carry over to the next buyer? Will they care?

@LuvsLEGO_Cool_J said:
"I don’t see bright bluish green (what fans call ‘teal’). Am I missing it? "

Teal had not been reintroduced by 2016, so that color along with dozens of other "retired" colors are not directly linked.

Fantastic article @Huw! Thank you!

What do you think about an article that explains how the set numbers were assigned in the 80's and 90's?

For example: the first wave of Pirates sets had the following numbers: 6235, 6245, 6251, 6257, 6260, 6265, 6270, etc. The second wave had 6234, 6259, 6267, 6273.

These numbers were not assigned sequentially. There were gaps between the set numbers for some "future reservation purposes". These gaps were always filled within the next years of particular series.

I'm wondering what was the system of assigning such numbers during the initial wave of particular classic theme. Did they plan that numbers from 6232-6237 are reserved for impulse sets, another range of numbers for some bigger sets, and bigger and bigger?

Based on the first years of Pirates sets we can discover that there is a relationship between the set number and it's box volume (I think).

@martinb said:
"Fantastic article @Huw! Thank you!

What do you think about an article that explains how the set numbers were assigned in the 80's and 90's?

For example: the first wave of Pirates sets had the following numbers: 6235, 6245, 6251, 6257, 6260, 6265, 6270, etc. The second wave had 6234, 6259, 6267, 6273.

These numbers were not assigned sequentially. There were gaps between the set numbers for some "future reservation purposes". These gaps were always filled within the next years of particular series.

I'm wondering what was the system of assigning such numbers during the initial wave of particular classic theme. Did they plan that numbers from 6232-6237 are reserved for impulse sets, another range of numbers for some bigger sets, and bigger and bigger?

Based on the first years of Pirates sets we can discover that there is a relationship between the set number and it's box volume (I think)."

Yes, that would be interesting. One on the 5-digit numbers might also be, and they are slightly easier to get to grips with.

As you say, the numbers initially gave come indication of the size of the set.

@greenhorn said:
"That's an absolutely impressive photograph of that blue 3032 plate, Huw! Macro lens or microscope? ;-)"

Panasonic G9, 30mm macro lens and plenty of light!

Calling the number visible on the part the Design Number is a little misleading. As you point out prints get a new design ID but the actual part will show what is better referred to as the Mold Number. You can’t find a prints design number on a part or in a BI so are largely useless to most LEGO consumers. They’ll see and search the mold number or EID in the BI’s.

You also excluded what most people call the batch number. These are numbers molded into parts and are usually 4digits with a dash in the middle (eg 40-67). These numbers are used by lego to track when and where faulty parts may have come from. It’s unlikely you’ll ever get two parts with identical batch numbers even in the same set. These often confuse new LEGO fans.

@mfg3000 said:
"Thanks, Huw! It's impressive that you can keep all that clear enough in your head to write about it so cohesively. The numbering system is interesting, though, and it's been helpful, albeit confusing, in trying to reconstruct sets from my nephews' decimated collection for their young children. I do have a question about what I think are element numbers that I see on Bricklink. Sometimes there seem to be lowercase letters in the middle of what I am assuming is an element number. and I always wonder what their significance is. Would you know what those letters mean? "

EIDs never have letters in. You are potentially looking at BrickLink’s part numbers which is commonly not LEGO related. For example, for printed 2x2 bricks they’ll use the number molded on the part plus a ‘pb’ to signify a printed part, followed by a number which is sequential from the first printed version.

EIDs almost exclusively begin with a 4 or a 6 (new EIDs have been 6’s for a couple of years now). There are exceptions to the 4&6 rule for really early EIDs, these usually break the 7 digit rule too.

@MasterT said:
"Great article, very interesting stuff. I do have a question on numbering on a piece. Is there a way to tell the color of piece by looking at the bottom? I am talking mainly about small 1X1 pieces in old grey and light blue grey for example. Those are sometimes very hard to tell the difference between them by just looking at the color like on bigger plates and bricks that are easier to see the difference in color. Sometimes I get a bulk bit of bricks and trying to see the difference in those as to how to sort them can be challenging."

Nope, no number on the part will tell you it’s color.

@shaase said:
"similar to 2012/13 when Lego ran out of numbers for sets and had to upgrade to 5 digit sets; given the number of new Designs and all the Patterns (printed parts) in the last decade, Lego must be running out of 5 digit numbers. Will be interesting to see what Lego decide's to do."
They have a while yet. There’s 90,000 different permutations of a five digit number, at best informed guess (can never be too sure with older LEGO and odd prints that turn up) there’s 140k parts since the fifties. While it’s true LEGO make far more new design IDs, it’s unlikely they’ll run out in the next decade.

@jaredhinton said:
" @mfg3000 said:
"Thanks, Huw! It's impressive that you can keep all that clear enough in your head to write about it so cohesively. The numbering system is interesting, though, and it's been helpful, albeit confusing, in trying to reconstruct sets from my nephews' decimated collection for their young children. I do have a question about what I think are element numbers that I see on Bricklink. Sometimes there seem to be lowercase letters in the middle of what I am assuming is an element number. and I always wonder what their significance is. Would you know what those letters mean? "

EIDs never have letters in. You are potentially looking at BrickLink’s part numbers which is commonly not LEGO related. For example, for printed 2x2 bricks they’ll use the number molded on the part plus a ‘pb’ to signify a printed part, followed by a number which is sequential from the first printed version.

EIDs almost exclusively begin with a 4 or a 6 (new EIDs have been 6’s for a couple of years now). There are exceptions to the 4&6 rule for really early EIDs, these usually break the 7 digit rule too.

"

Thank you, that makes so much sense. I should have been able to figure that one out!

@Huw said:
"^ I've asked many times over the years to talk to the department that issues set numbers but to no avail, sadly..."

Hey @huw I have worked several years in the plastic industry and while I have never worked for Lego themselves, I can give you a little more insight into how companies come up with these numbers if you are interested.

From my understanding 88585 designates torsos that are exclusively produced in China while 76382 is for all torsos with single-color arms, presumably because they are produced in factories worldwide.

During 88585s introduction in 2010 the arms had square markings molded on the inside, somewhat visible but not really apparent until you disconnected the arms. They were only put into figure-centric sets like CMFs and Accessory Packs. You could easily tell these parts apart from other countries because of the excessively milky tinge. The same style of arm has also began being used earlier, in Magnet Sets, the kind without glue but with 2x4 magnet bricks.

During 2013 the number started designating torsos with printed arms alongside CMF exclusive torsos for which it has been used consistently since. Between 2011 and 2013 the arms lost the square markings and both, the 76382 and 88585 torsos started using arms with numbers on their inside but the exact placement of the numbers has multiple variations.

Before 2009 arms had no markings whatsoever, not even the regular design number which would be 3818/3819. The first time I spotted square marked arms was in January 2009, 852554 Magnet Set Vader/Chewbacca/Obi-Wan. It appears those sets still used the number 76382 internally because the parts were always in production due to other sets using the same torsos going into production earlier or simultaneously and the new number only came in effect once China produced exclusive torsos. Probably has also something to do with the logistics of getting those parts into Europe and have them available in Replacement Parts Service or packed into sets with otherwise only locally produced elements in europe or america.

In my opinion these China produced pieces should always have used a different design number because of the new arm molds clearly making it a different parts and because the plastic has a milky tinge even to this day albeit not as prominently as it once was. Chinese factories introduced even more oddities than just this, for example there is also a Darth Vader torso with a print where metallic colors have been replaced with ark bluish grey. That might have been a first-run error of my copy as I have never seen anybody else acknowledging this variant.

@CCC said:
"It is interested to look at the numbers on bricklink. At some stage someone got confused between mould numbers and parts numbers. There are some homemaker parts with numbers below 10. There is even a part number 1!"
Bricklinks (and almost all other fan sites) numbers came from Peeron (before that stopped being updated). I believe they were largely created by one man in the 90’s (I forget his name but I think it’s Bill something) who decides he wanted to catalogue all lego parts. He used mold numbers where possible and made up numbers when there was no mold number.
This was before lego made any information available to the public, not design IDs or even element IDs.
Any catalogued parts pre 1995 are largely thanks to one mans effort.

Just scrolling through the two lists of torsos, one thing is very clear to me. 88585 includes a ton of CMF torsos, while 76382 does not. So, the former is probably the Chinese mold, and the latter is probably a European one.

The reason why the elements are named rather than the designs is probably due to picking systems. The mold and the color are the critical bits of knowledge on the production floor, as they have no idea, in some of these cases, what the eventual element will look like (if it's printed or not, or which parts it will be combined with if it's an assembly). When you're picking parts, the element ID number is basically going to be used like a SKU. Type the number into a computer, and it will tell you where in the warehouse those elements are located. If you're picking parts, you would see the element name on the screen, which you would use to verify that you're picking the correct element. Since the same design can end up being used across a range of elements, it makes more sense to name the elements over the designs.

@Librarian1976:
An element ID number is just a number. It's used to inventory elements internally while they wait to be packed into sets, or shipped out to customers who order replacement parts or B&P/Online PAB. It's not actually attached to the physical part, so there's no way to tell which element ID number that element shipped as, unless it has gone through variations that match up precisely with those EID changes. Take, for instance, the 2x4 brick. It has gone through several mold changes over the years, but as long as a red 2x4 stays in production it will never be assigned a new EID. Therefore, you can't tell anything useful from that number beyond the basic shape, the basic color, and the fact that it's unprinted. The 1x2 jumper plate, on the other hand, has gone through two mold changes in quick succession (introducing the tile-style lip to the edge, and completely redesigning the underside so it'll attach to a single solid stud in the center). If the jumper plate was released once in a color while the original design was in production, taken out of production for a few years, released one more time during the short window with the second design, back out of production for a few years, and a third time after the second change was made, you'd be able to match up all three sets that it came in with the specific design that was in production at the time. That would then allow you to determine the precise element ID number used for each version...but if someone really cares about it that much it's far easier to just ask by description than expecting anyone to be able to determine exactly which element ID number was applied to every part in their collection.

@MasterT:
Change your lighting. Seriously. Incandescent lights are the worst for telling greys from bleys. Cool white fluorescent works great, if you can stand it. I prefer daylight spectrum LED (previously used CFL), and you want bright light (so aim for 100w equivalent). But no, the part molds are not modified whenever they do a color swap. They also don't stamp the parts afterwards to record that information. If it's seriously in question, I suspect they use some sort of color spectrometer to identify the precise color they're looking at.

@meesajarjar72:
No, the plural of LEGO is LEGO _bricks_. Or LEGO parts. Or anything that treats the world "LEGO" as an adjective:

"Proper Use of the LEGO Trademark on a Web Site
If the LEGO trademark is used at all, it should always be used as an adjective, not as a noun. For example, say “MODELS BUILT OF LEGO BRICKS”. Never say “MODELS BUILT OF LEGOs”."

Taken from https://www.lego.com/en-us/legal/notices-and-policies/fair-play/

@mfg3000:
That's usually part of an internal numbering system used by Bricklink. Part assemblies are marked by the inclusion of letters. Decorated parts are marked by the inclusion of letters. They strictly catalog everything by the mold design numbers, and sometimes those numbers weren't publicly available when the part was added to their catalog, so some parts use made-up numbers just to have a way to identify them. There might be a few other reasons why letters would be included, but any catalog number you see that includes letters is at least partly made up by the AFOL community. In part, this helps keep the system from breaking. If they had been assigning special catalog numbers by adding a single digit to a four-digit design number, things would have gotten messy the instant five-digit design numbers started being used. But using letters (which The LEGO Company does _not_ use) means there should never be any conflict between the two systems going forward.

@jaredhinton:
Those aren't batch numbers, since it would be prohibitively expensive to change those numbers out every time you ran a new batch, and you can't see evidence of changeable typeface impressed into the parts. My understanding is that those identify exactly where a part was molded. Usually these numbers are in - format, or sometimes just a by itself (the Poisoned Hau Nuva mask from Bionicle needed a special mold and was only intended for a limited run, so they only made one 4-up mold, and only molded the cavity numbers into the parts since every instance of that part was produced on the same mold). The double-digit numbers are used to identify the mold (multiple copies of a mold may exist because older molds wear out, because a particular design is in such high demand that they need to be able to run multiple colors at once, or because they have molds in different countries to save them having to ship the molds all over the world). The single-digit numbers identify the specific cavity in which that part was formed. So, 2x4 bricks are produced on an 8-up mold, meaning each time you open the mold it will eject eight new 2x4 bricks. The mold that's currently producing parts may be 42, which will eject parts numbered 42-1, 42-2, 42-3, 42-4, 42-5, 42-6, 42-7, and 42-8. This allows them to track a defect to exactly what part of which mold needs to be repaired or replaced. Incidentally, 2x4 bricks have gone through a truckload of molds over the years. I just pulled a dark-purple 2x4 brick that I used to build a transport puck for a MOC I built in 2014 (so it's at least 6.5 years old), and the mold/cavity number is 4-246. So, they've made enough 2x4 bricks that they'd worn out roughly 240 molds by the time that part was produced.

@CCC:
It depends on personal preference which is better. I build MOCs, so I need to be able to navigate the Bricklink catalog with far greater ease than I'd ever need this one for. Brickset allows you to catalog your entire collection, though, so someone who desires that more would prefer this system.

@Judge_Fudge:
Print differences are probably a lot more common between retail set minifigs and other sources than people think. The one I noticed was that the Lou Ferrigno Hulk had dark-green muscle print on the polybag minifig, but black muscle print on the keychain.

@CCC:
The founder of Bricklink added the parts numbered "1" and "2" to the catalog, so presumably he knew what he was doing. Rebrickable and Peeron use the same numbers for those parts, which is further evidence that he didn't screw up. Bricklink part numbers that start with a lower-case "x" are used to catalog parts with unknown design numbers. That numbering system didn't start until x11, so parts 1, 2, 3, 5, and 8 appear to be predecessors to that numbering system, while part 10 was a baseplate where the corners were either squared or rounded.

@PurpleDave said:
" @CCC:
The founder of Bricklink added the parts numbered "1" and "2" to the catalog, so presumably he knew what he was doing. Rebrickable and Peeron use the same numbers for those parts, which is further evidence that he didn't screw up. Bricklink part numbers that start with a lower-case "x" are used to catalog parts with unknown design numbers. That numbering system didn't start until x11, so parts 1, 2, 3, 5, and 8 appear to be predecessors to that numbering system, while part 10 was a baseplate where the corners were either squared or rounded."

It was actually Bricklink that copied Peeron. They also ‘borrowed’ all Peerons part and set images which allowed Bricklink to immediately be a useful tool for AFOLs. Without Peeron bricklinks growth would have been significantly slower. They benefited greatly from a solid community of AFOLs right as LEGO were experiencing their dark days. AFOLs today owe so much to those LEGO fans in the 90’s who were so dedicated to preserving the hobby even when so many people were getting less interested.

@jaredhinton:
What I meant was, if you go to the catalog pages, "Admin" is credited with adding the bookcases to the catalog and uploading the images. I wasn't aware that they lifted images to get started, but I didn't register until mid-2003 while the site was founded in 2000. At some point under the second owner, Bricklink changed their ToS to claim ownership of any images used in the catalog entries. As part of that change, they required any previous contributors to release the rights to their images so they would fit the new norm. If you gave them permission, it was like submitting a new image under the new ToS. If you denied them permission, they removed them and started replacing them immediately. If you couldn't be contacted, or chose not to respond, they were probably a little less urgent about it, but did eventually replace all of those images as well. So, at this point, any images that were lifted from Peeron are either gone, or they've actually received permission to keep them.

I also remember that, at the time, there were three competing part catalogs running. Bricklink is by far the most successful of the trio, Peeron is no longer being updated (but is still available to browse), and LDraw was...a bit weird. At the time they relied not only on volunteer contributors, but those contributions required a lot of digital design work. There was some sort of agreement for a time that, if someone else had already added a part to their catalog where the design number was unknown, the other two sites would use that same catalog number to maintain some degree of consistency between the three catalogs. I suspect at some point Bricklink just started doing their own thing, but these days it's less of an issue as design numbers are readily available for any new molds.

And I don't know what 90's you experienced, but that was really the birth of the AFOL community. Prior to that, there were people all over the world who would be recognized as AFOLs by today's standards, but very few of them were aware that they weren't alone. It was really the birth of the World Wide Web in the early 90's that brought internet access out of the domains of academia and the military into private homes that allowed the AFOL community to start coming together. The 90's weren't about preserving content, but about creating community, figuring out exactly what it meant to be an "AFOL", and developing new resources to help an undeveloped hobby grow. So, like the Rosetta Stone, these resources were not developed to preserve knowledge for future generations so much as they were to make it available for the present. Yes, older sets going all the way back to the development of the LEGO System have been cataloged, but one of the main benefits of a site like Peeron is that it made current set inventories available to the public. There was no equivalent to it when the site got started two years before Bricklink went live. Digital instructions and set inventories were something The LEGO Company wouldn't get behind for probably at least a decade, and Peeron even had to agree to delay posting instructions for new sets for a period of years so they wouldn't hurt sales of those sets. Yes, the newest generations of AFOLs owe a debt to those who came before them, but content has always been generated for the present. Nowhere is this more evident than with Bricklink. Sellers can't list items until they're entered in the catalog, and buyers don't have access to them until they can buy them. The result is that new catalog entries are driven by a desire to generate sales. Later generations may see decreasing benefit over the years to come, but the most immediate benefit comes to the seller who generates the catalog entry, and the greatest benefit comes to those other sellers who are able to list their own sets and parts until shortly after the set is retired. As the supply dries up, the content sees a pronounced drop-off in its usefulness.

@Galaxy12_Import said:
"From the outside we can only guess what is going on at LEGO HQ, but very interesting to see that there has been an attempt at a cohesive design+color scheme, at least early on.

As a data guy this article sums up a lot of what I have pieced together and draws some connections I hadn't made yet, and the timeframes are always nice to know.

As a database that actually tracks all of these details, Brickset is in the perfect position to bring a dose of insight to this side of the hobby, thank you for the effort and dedication to doing things by the book.

--Nathan"

Exactly what he said.
--Joshua

@Librarian1976 said:
"This article is filled with great information. Thanks!
I've been wondering for the past few years how much small variations in elements matter to people, specifically to collectors. I have recently started parting out the retired Modular Buildings that I missed out on. The first one I parted out was 10224 Town Hall, for which I needed 72 of element 4164443-1 (Brick 1X3 in dark orange). This element was retired in 2012 and sold for a pretty penny on BrickLink. Luckily, as I was still collecting the elements for my Town Hall LEGO reintroduced this element with a new number (6263221) so I was able to get the newer numbered ones directly from LEGO's Bricks & Pieces for a fraction of what the older numbered ones were going for on BrickLink. Are there collectors out there who are that detail oriented that my using the newly numbered element would impact the resale value of my set? What about a non-identical element that is a slight variation on the underside. For example, a 1x2 jumper with bottom type A vs. bottom type B vs. bottom type C?"

I'd say some care, some don't :) Personally, when I try to piece together a set from for example the 70's I make sure I get the period correct parts, as far as is reasonable. When it comes to newer sets, I do look at details like tile with or without groove. And for your example, if the part was in production when the set was released I'd say it's fair game whichever you choose. Lego themselves haven't been consistent over the years when older designs are in production alongside newer designs. So my recommendation, if the version of the piece was in production when the set was sold from Lego, just go ahead. I'd try to make sure all pieces of the same kind in the set are of the same version though :) Of course, just my opinion!

@Zatth said:
"It's been mentioned above by the perceptive joshcvt, but I too highly doubt that "links" is a typo. It's probably deliberate German for "left". Most likely a designer/tech slipped into his native language."

Or Dutch. "Links" in Dutch also translates to "left".