How to identify a LEGO part you cannot name

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Building & parts 6 min read

Loose LEGO parts are the hardest thing to look up, because a part has a number that is almost never printed on it. The trick is to describe it the way the catalogue does, then narrow down from there.

Describe it by studs and family first

Every catalogue name starts with a shape family and a size in studs. Count the studs along each edge and decide which family the piece belongs to before you try to name the piece itself.

  • Brick — as tall as three plates
  • Plate — one third the height of a brick
  • Tile — a plate with a smooth top, no studs
  • Slope — an angled top face
  • Wedge — angled in plan view as well
  • Technic — holes for pins and axles rather than studs

Get the colour name right

Colour names cause more failed searches than shapes. Light bluish grey and dark bluish grey replaced the older greys in the mid-2000s, tan and dark tan are distinct, and reddish brown is not the same as brown. If two candidates differ only by shade, compare against a piece you already know.

Check printing and moulding marks

Printed parts are separate catalogue entries from plain ones, so note any printing, stickers, or moulded detail. If a piece is printed on one face only, that detail alone will usually take you to the exact part rather than a family of similar ones.

Photograph the pile instead of typing

For a tub of mixed parts, the photo identifier accepts several pictures at once and returns candidate parts, figures and sets with a confidence level and alternatives. Anything it gets wrong can be corrected by hand before saving, so a bad guess never becomes a bad record.

Good photos matter more than good lighting equipment: spread pieces out so none overlap, shoot straight down on a plain background, and keep the shot close enough that printing is legible.

Confirm with set appearances

Once you have a candidate part, check which sets it appeared in. If none of them could have been in your house, you almost certainly have a similar part in a different size or shade — that cross-check catches most mistakes.

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