Are LEGO Alternatives Compatible With LEGO? Brand by Brand
Supporting Free Content
When you purchase through our links, we earn a small commission at no extra cost to you. As an Amazon Associate and eBay Partner, this helps us keep bringing you expert LEGO® reviews and guides. Thank you for your support!
Most LEGO alternative brands are built to fit LEGO bricks, but fit is not the same thing as identical. This guide goes brand by brand through MEGA, COBI, CaDA, Mould King, JMBricklayer, Reobrix, BlueBrixx, Lumibricks, Sluban and Nanoblock, and covers what actually differs when you mix them, from clutch and colours to figures and motors.
Yes, most LEGO alternatives are compatible with LEGO bricks. The last patents on the LEGO brick expired in 1978, and almost every rival brand since has built to the same stud spacing so its bricks can join a LEGO collection. Compatible is not the same as identical, though: grip, colours, figures and electronics are where the brands differ, and two well-known names, Nanoblock and preschool MEGA Bloks, are separate systems altogether.
This guide answers the compatibility question brand by brand. If you want to know which alternative is worth buying instead of LEGO, on price, quality and motors, read our full comparison of LEGO against CaDA, Reobrix, MEGA and JMBricklayer. Everything below draws on manufacturer statements, retailer descriptions and published reviews, cited by name; it is research, not a lab test.
Why rival bricks fit LEGO at all
The interlocking stud and tube design was patented, and the last of those patents expired in 1978. Courts have since treated the studs as a technical function rather than a trademark: in 2010 the European Court of Justice ruled that the shape of the LEGO brick could not be registered as a trademark for that reason. That is why MEGA, COBI and dozens of newer brands can legally make bricks that press onto LEGO ones, and why most of them advertise exactly that.
Lumibricks, one of the newer brands, publishes the numbers it builds to: a stud pitch of 8.0 mm, a brick height of 9.6 mm and a plate height of 3.2 mm, so three plates equal one brick. Those are the same dimensions LEGO uses, and they are the reason a compatible brick stacks on a LEGO one without a gap.
Compatibility at a glance
| Brand | Fits LEGO bricks | Figures | Watch for |
|---|---|---|---|
| MEGA (formerly MEGA Construx) | Yes | MEGA's own design | Some joints grip less tightly; specialised parts can fit imperfectly |
| MEGA Bloks (preschool) | No, a larger system | None | Not reliably compatible with DUPLO either |
| COBI | Yes | Fit LEGO, but no stud holes under the legs | Parts reported slightly tighter than LEGO |
| CaDA | Yes, Technic parts included, per its retailers | Not documented | Motorised models use CaDA's own motor kits |
| Mould King | Yes | Not documented | Electronics use Power Functions style plugs, not Powered Up |
| JMBricklayer | Yes | Not documented | Long thin parts flex more; own remotes and app |
| Reobrix | Sold as compatible | Not documented | Fewer independent reviews; own remote and app |
| BlueBrixx | Yes | Not documented | Also resells CaDA, COBI and Xingbao |
| Lumibricks | Yes, to LEGO's dimensions | Its own design | Special colours may differ; built-in lights |
| Sluban | Yes | Not LEGO compatible | Lighter bricks |
| Nanoblock | No | None | A smaller scale with a different connection |
For a known reference point, a plain LEGO brick box is the easiest way to see how any of these feel next to the real thing:
A large box of standard LEGO Classic bricks with ideas for vehicles. The plain System bricks every compatible brand is built to fit.
MEGA, MEGA Construx and MEGA Bloks
The name causes most of the confusion. Mattel's line for older builders was MEGA Bloks, became MEGA Construx in 2017 and is now sold simply as MEGA, the home of its licensed Halo, Fallout and, until the end of 2025, Pokémon sets. When MEGA Construx launched, its maker stated that all sets would be compatible with existing standard size bricks, so ordinary MEGA bricks and plates press onto LEGO.
Reviewers add two caveats. Little Upgrades notes slight differences in MEGA's studs and holes that can make a MEGA to LEGO joint a bit less firm than LEGO to LEGO, and that some pieces do not fit quite right. Its figures are a different design, with arms that the same review says break more easily. MEGA is fine to mix for walls, bases and filler; check clips, hinges and figure accessories before relying on them.
MEGA Bloks is now the preschool brand of large blocks for ages one to five, and it is not standard brick size. Whether those blocks work with LEGO DUPLO is disputed: one guide describes them as close to DUPLO and loosely stackable, another says DUPLO will not sit on top of them. Treat them as their own system. If you are choosing between the two for a toddler, our DUPLO versus regular LEGO guide covers when to switch.
A small LEGO DUPLO brick box. DUPLO bricks join regular LEGO bricks, which preschool MEGA Bloks do not promise.
Mattel also launched a separate building brand, Mattel Brick Shop, in 2025, starting with seven Hot Wheels car sets. Its launch coverage made no compatibility claims, so we have left it out of the table.
Browse MEGA building sets on Amazon
COBI
COBI is a Polish brand known for historical military models, tanks, aircraft and warships, along with licensed sets. Its bricks use the standard brick size, and the UK reseller Brick Tanks, which stocks both brands, says it cannot tell COBI and LEGO bricks apart for quality and fit. Latericius goes further and reports that COBI pieces fit together slightly more tightly than LEGO's. COBI also prints its details instead of using stickers.
The difference is the figures. COBI figures are described as compatible with LEGO, but they have no holes for studs underneath the legs, so they do not sit on a LEGO plate as securely as a LEGO minifigure. They are also styled more realistically, with shorter legs. If you want COBI soldiers in a LEGO scene, expect them to stand rather than lock in place.
LEGO sued COBI in Poland around the turn of the millennium and lost; the courts found COBI's bricks were original rather than copies.
CaDA
CaDA is made by Double Eagle, a Chinese toy company based in Shantou that dates from 1988. TrackBricks, a French CaDA retailer, describes its bricks as fully compatible with LEGO Technic, and lists official licences from car makers including Mazda, Lotus, Toyota, Audi and Mercedes-AMG. That is a seller's claim rather than an independent measurement, so if a build depends on a particular LEGO Technic part, try the fit before committing.
Motorised CaDA models run on CaDA's own motor kits, which are not documented as working with LEGO's hubs. Plan a motorised CaDA build around CaDA electronics.
Mould King
Mould King makes large Technic-style vehicles, engines and machines, many of them motorised. BrickSewer, a retailer that sells Mould King, says its bricks use the standard stud and tube system and interlock with LEGO, and both BrickSewer and Latericius say the parts come from GoBricks, a parts maker whose colours one MOC designer describes as very close to LEGO's.
The electronics are where compatibility gets specific. Mould King's control boxes, such as the M-0006, use the same style of plug as LEGO's older Power Functions system and can drive official Power Functions motors, according to the open-source Espruino project that documents them. LEGO's current motors use the Powered Up plug, a different connector, so a Mould King box is not a drop-in part of a Powered Up or CONTROL+ model. If you are curious how LEGO's current plug works, our guide to the Powered Up connector explains it.
Browse Mould King sets on Amazon
JMBricklayer
JMBricklayer sells display models and remote-controlled vehicles with the motors included. The Gadgeteer found its bricks totally compatible with LEGO, connecting exactly as a LEGO brick would, with Technic-like connectors that are stiff and hold well. The same review noted that long thin pieces, such as a 1 by 8 plate, are noticeably more flexible than LEGO's. The remotes and apps are JMBricklayer's own. Our JMBricklayer versus LEGO comparison covers the brand in depth.
Browse JMBricklayer sets on Amazon
Reobrix
Reobrix makes big mechanical models: excavators, engines, helicopters and ships. Its sets are sold as LEGO compatible, and retailer write-ups describe the parts as well moulded, but there are fewer independent reviews of Reobrix than of the brands above. Its motorised excavator, for example, uses Reobrix's own 2.4 GHz remote and phone app rather than anything from LEGO. For a price and quality comparison, see the Reobrix section of our alternatives comparison.
LEGO's own motorised Technic excavator: one motor drives four functions through a gearbox. The LEGO answer to the big Reobrix and Mould King machines.
BlueBrixx
BlueBrixx is a German company founded in 2018 and based in Floersheim am Main. It sells its own LEGO compatible bricks and display models, including licensed Star Trek and Stargate sets, and also resells other brands such as CaDA, COBI and Xingbao.
Lumibricks, Sluban and other brands
- Lumibricks builds to LEGO's published dimensions (above) and is known for sets with built-in LED lighting. Its own guide says core colours such as black, white and greys are very close to LEGO's, while special colours may differ. One guide lists it as the brand that used to sell as Funwhole.
- Sluban bricks are compatible with LEGO but lighter, according to Tiny Workshops, and its newer figures are not compatible with LEGO minifigures.
- Wange bricks are compatible with LEGO, according to the same guide.
- Best-Lock bricks connect to LEGO bricks, and Hasbro's discontinued Kre-O line, sold from 2011 to 2017, was also built to fit.
Nanoblock: the one that does not fit
Nanoblock, from the Tokyo toy maker Kawada, is a micro-scale system. Its smallest brick measures 4 mm by 4 mm by 3 mm, and the bricks join with a double-ridged backing instead of LEGO's tubes, so a Nanoblock brick does not connect to a LEGO one. It is a different hobby: very small, detailed models built mostly for display.
Browse Nanoblock kits on Amazon
What actually changes when you mix brands
Grip
Most compatible bricks hold well, but not identically. Reviews above put COBI slightly tighter than LEGO, some MEGA joints slightly looser, and JMBricklayer's long thin plates more flexible. In practice that matters most in large spans and load-bearing parts. Use one brand for the structure that carries weight and mix freely in detail and decoration.
Colour
Shades are not standardised between brands. Lumibricks says its black, white and greys are very close to LEGO's while special colours may differ, and GoBricks colours are described as close enough that some need a side-by-side comparison to tell apart. Put mixed-brand parts inside a build or in places where the shade difference will not show.
Figures
Each brand designs its own figures. COBI's fit LEGO but do not lock onto studs, MEGA's are a different design, and Sluban's newer figures are not compatible at all. Do not assume LEGO hair, hats and accessories will fit another brand's figure.
Motors and electronics
This is where brands do not mix. Mould King and several other brands use the older Power Functions style plug; LEGO's current motors use Powered Up; JMBricklayer and Reobrix use their own remotes and apps, and CaDA its own motor kits. Plan each motorised model around one brand's controller rather than assuming plugs and apps will cross over.
Keeping a LEGO set complete
If you might sell a LEGO set later, keep its own pieces with it. Mixing other bricks into your general collection is fine; mixing them into a boxed set's inventory makes it harder to sell as complete.
Which to choose
If you want to add bricks to an existing LEGO collection, any of the brick brands above will fit. If you want figures to share scenes with LEGO minifigures, stay with LEGO. If you want motors to work together, stay inside one brand's system. And if you are deciding which alternative to buy in the first place, our LEGO versus CaDA, Reobrix, MEGA and JMBricklayer comparison compares price, quality and motors side by side, and our RC building block guide covers remote-controlled builds.
Use Our Tools to Go Further
Get more insights about the sets mentioned in this article with our free LEGO tools