How Do I Identify a LEGO Part?
To identify a loose LEGO part, describe what you can measure — its colour, its basic shape, and its size in studs (the bumps on top) — and match that against the LEGO parts catalog. A 2×4 brick, for example, is two studs wide and four studs long. Once you know colour, shape, and size, only a handful of parts remain, and each one carries a part number you can use to find a replacement.
Here are the common ways to do it.
How are LEGO part sizes measured?
LEGO sizes are described in studs: width × length, sometimes with a height. Count the studs along each edge of the piece — that gives you the dimensions you'll search by.
- Good for: standard bricks, plates, and tiles where the studs are easy to count.
- Falls down on: curved, sloped, or oddly shaped pieces where "size" isn't a clean grid.
Browse a parts catalog by category
Open a LEGO parts database, pick a category (bricks, plates, slopes…), filter by colour, and scroll until you spot it.
- Good for: when you already know the rough category.
- Falls down on: categories are huge. Scrolling hundreds of grey plates to find the right one is slow, and you have to guess which category the part belongs to in the first place.
Ask a community
Post a photo to a LEGO forum or subreddit and let enthusiasts name it.
- Good for: rare or unusual parts that stump search.
- Falls down on: you have to wait, and it doesn't scale if you have a tub of mystery pieces.
The easy way: Afolio's Identify a Part tool PRO
Afolio lets you describe the piece and narrows the parts catalog as you go. Open Identify a Part:
- On iPhone: tap Identify a Part under Tools on the home screen. It opens full screen, which is handy with the brick in your other hand.
- On iPad: tap Identify a Part under Tools at the bottom of the sidebar.
- On the Mac: choose Tools → Identify Part… (⌘⇧P).
Then set what you can see:
- Colour — pick one or more colours, with a separate toggle for transparent pieces of any hue.
- Shape — choose one family: brick, plate or tile, curved, round, wheel, window or door, panel, plant, animal, sticker, or Technic.
- Dimensions — type the stud dimensions. Order doesn't matter, so entering 2 and 4 finds a 2×4 part whichever way you measured it, and partial input still works — entering 2 and 4 matches both a 2×4 plate and a 2×4×3 brick.
- Attributes — toggles for Technic, curved, sloped, and where the studs sit (top, side, bottom).
- Name contains — a keyword if you know part of the name.
A live count updates as you add filters. When 100 or fewer parts match, a grid of candidates appears. Tap or click one to see its image, name, and part number, then choose Reveal in Catalog to open the part and see which sets it comes in. The part number is what you'll use to find a replacement at a pick-a-brick wall or on a marketplace.
Trying to recognise a whole set instead of a single piece? See how to identify a LEGO set. Working through a used set and need to know what's missing? Use the parts checklist.
Try it yourself
Afolio tracks your LEGO collection on Mac, iPhone and iPad, with free iCloud sync between them. It's free for up to 25 sets, and Pro is a one-time upgrade with no subscription.
Prefer not to use the Mac App Store? Download the Mac version directly.
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