Brick Part Number Lookup: A Complete Guide for MOC Builders

There is no way around part numbers. If you design your own MOC, the number is what you order against. If you build someone else's instructions, the number is how you find the piece. Look things up slowly and an entire evening disappears into digging through bins. This guide walks through brick part number lookup end to end — the numbering systems, the categories, and a practical workflow you can use tonight.

The Brick Part Numbering System at a Glance

Brick part numbering has developed over decades into a fairly complete coding system. Understanding it is the first step in learning the full catalogue of brick part names.

The main numbering systems

Four systems cover most of what a builder needs:

1. LEGO Design ID — the unique number LEGO assigns to each part, usually 4 to 7 digits. It is the most authoritative reference standard.
2. Bricklink number — the system used by Bricklink, the largest brick trading platform in the world, covering nearly every known part.
3. Rebrickable number — the number used by MOC instruction platform Rebrickable, cross-searchable with Bricklink numbers.
4. Gobricks part number — Gobricks is the largest brick parts supplier in China, and its numbering is widely used by MOC builders there.

How a part number is structured

Take LEGO Design IDs as an example. A typical part number maps to one specific element:

3001 → standard 2x4 brick
3003 → standard 2x2 brick
3622 → standard 1x3 brick

The numbers themselves do not follow a strict classification rule, but with enough exposure you start to recognize the common ones by sight. That is exactly when a full brick part category chart becomes important.

Brick Part Categories Explained

Knowing the categories is the foundation of fast lookups. Seen through the lens of a brick part category chart, parts fall into these groups:

1. Bricks

The most basic building unit, including:

• Standard bricks: 2x4, 2x3, 2x2, 1x2, 1x1 and so on
• Modified bricks: curved bricks, decorated bricks and similar
• Corner bricks: 1x1 corner, 1x2 corner and so on

2. Plates

Flat parts one third the height of a brick:

• Standard plates: 2x4 plate, 2x2 plate, 1x2 plate and so on
• Special plates: notched plates, plates with handles and similar

3. Slopes

Parts used to build roofs, ramps and angled shapes:

• Standard slopes: 45-degree slope, 33-degree slope
• Inverse slopes: 45-degree inverted slope and similar
• Curved slopes: 1x2 curved slope and similar

4. Technic

Parts used to build mechanical structures:

• Beam: the long part with holes
• Pin: the connector
• Gear: gears in various sizes
• Axle: the drive shaft

5. Decorative and specialty parts

This covers themed parts such as windows, doors, plants, minifigures and animals.

Every Way to Look Up a Brick Part Number

Method 1: Official databases

Looking up a part on Bricklink Bricklink is the largest brick part trading platform in the world and the most commonly used lookup tool:

1. Go to the Bricklink website
2. Type a part description into the search box (for example "2x4 brick")
3. Find the matching part number in the results
4. Check that part's colour list, price history and stock information

Looking up a part on Rebrickable Rebrickable hosts MOC instructions but also has a strong built-in parts database:

1. Search the Rebrickable parts database
2. Reverse-search a part number to get its name and image
3. See which sets the part appears in

Method 2: Visual identification

If you have the part in hand but no number, try these:

1. Browse a picture gallery — work through Bricklink's category pages by shape
2. Measure it — count the studs to establish the basic dimensions
3. Photograph it — some phone apps support photo recognition of brick parts

Method 3: Use a brick part name reference

A good brick part name list lets you pin down a part quickly. On brickplan.cn we maintain a name conversion table for common parts, covering Chinese and English names, numbers and category information, so builders can look things up fast.

Method 4: Gobricks part lookup

Gobricks parts are one of the most common part sources for MOC builders in China. To look them up:

1. The Gobricks website — browse the parts library by category
2. Cross-reference the numbers — Gobricks numbers map to Bricklink numbers, so a conversion table will carry you across
3. The mini program — the official Gobricks WeChat mini program supports scanning a part to look it up

In Practice: A Part Lookup Workflow

Say you have downloaded an MOC instruction from brickplan.cn and need the number for one of its parts. Here is the workflow to follow:

Step 1: Check the parts list in the instructions (usually a Bricklink number)
Step 2: Search that number on Bricklink to confirm the part image
Step 3: If you are buying Gobricks parts, convert the number with a Gobricks cross-reference table
Step 4: Confirm colour and quantity, then add it to your shopping list
Step 5: Search the number on a marketplace and buy

Fixing common lookup problems

Q: The number does not exist at Gobricks — what now? A: Look for a substitute. Most standard functional parts have equivalents from several brands: same function, different number.

Q: Two parts look almost identical but have different numbers. A: Compare the details closely — dimensions, stud placement, whether there is any decoration. A tiny difference can be enough to split the number.

Q: The old part number does not match the new one. A: LEGO updates its numbering from time to time, and old numbers can be retired or merged. Rebrickable's compatibility search is the place to check.

Small Habits That Speed Up Lookups

1. Keep a list of your common parts — build a table of the numbers you use most
2. Use bulk lookup tools — Bricklink and Rebrickable both accept uploaded part lists
3. Watch for numbering updates — check in on part number changes periodically
4. Lean on the community — experienced builders in brick communities are happy to share how they search

Quick-Reference Table of Common Part Numbers

For fast lookups, here is a short reference table of common parts:

Part name	Bricklink No.	LEGO Design ID	Gobricks No.
2x4 brick	3001	3001	GB001
2x2 brick	3003	3003	GB002
1x2 brick	3004	3004	GB003
2x4 plate	3020	3020	GB101
2x2 plate	3022	3022	GB102
1x2 plate	3023	3023	GB103

Wrapping Up

Knowing how to look up a brick part number is a required skill for any MOC builder. Going from manual searching to fluent use of the tools takes some practice and exposure, but once it clicks, both your MOC output and your enjoyment go up noticeably.

If you want more MOC instructions or parts reference material, brickplan.cn has a large instruction library and a parts knowledge base worth browsing next.