How to Check Whether a Used LEGO Set Is Complete

To check whether a LEGO set is complete, first identify its exact set number, open the inventory, and compare elements by part number, color, and quantity. Count spare parts separately — a missing spare does not mean the main model is incomplete. For a larger set, divide the work into categories and record your progress.

BricksIndex displays set information, the parts inventory, and spare elements separately. Once you have recorded the bricks you own in a warehouse, you can use build analysis to prepare lists of available and missing elements.

Search for a set number in the BricksIndex catalog

When should you check a set?

A completeness check is particularly useful when you are buying a used set, taking out a model that was dismantled several years ago, preparing an accurate description before selling, or planning to rebuild it from a loose collection.

Before buying a used set, ask the seller how its contents were checked. “It should be complete” does not mean the same thing as a comparison against the exact parts inventory.

1. Identify the exact set number

The set number is usually printed on the box and the instruction booklet. In catalogs, it may include a suffix such as “-1” that identifies a specific record variant.

Do not rely on the name alone. Sets with similar names may differ by release year, sales market, or contents. The exact number reduces the risk of comparing your set with the wrong inventory.

If the box and instructions are missing, begin with the most distinctive elements, stickers, or minifigures. A basic brick used in hundreds of models will rarely identify a set unambiguously.

2. Open the parts inventory

Search for the number in the catalog and open the set page. The inventory should list the part number, name, color, required quantity, spare parts, and assigned minifigures.

Pay attention to both the color and the part variant. Two elements with a similar shape may have different numbers or a small structural difference. A similar substitute may work in a build, but for a collector's assessment it is not the same as the element originally included in the set.

3. Separate spare parts

Small elements are sometimes included as spares. These may be small plates, pins, tiles, or accessories. Their exact number often causes confusion.

1. First check all elements required for the main build.
2. Only then compare the spare parts.
3. In a sales description, report the condition of the model and the spares separately.

A missing spare plate will not prevent you from building the model, but it may matter to someone who expects the entire package to be complete for collecting purposes.

4. Sort elements before counting

Do not count parts directly in a large mixed container. First separate large and distinctive elements, basic plates and bricks, Technic parts, decorative elements, minifigures, and very small parts.

You can use shallow trays, resealable bags, or small containers. A light background makes transparent and dark elements easier to see.

For larger sets, sort by type first and then by color. Looking for a small black element in a container holding every black brick will usually take longer than searching a group of parts with similar shapes.

5. Record your progress

The simplest method uses three states:

• complete — the quantity is correct;
• partial — the part is present, but several pieces are missing;
• missing — no pieces were found.

Do not return checked parts to the shared container. Place them in a labeled bag or location so that you do not count the same element twice.

In BricksIndex, you can assign parts to a specific warehouse, box, or compartment. Set analysis compares the recorded contents with the build requirements and separates available and missing elements.

Create an account and save the parts you have checked

6. Check minifigures, printed parts, and stickers

A complete set includes more than the basic bricks. Separately check the torso, legs, head, headgear, and accessories of each minifigure, as well as printed elements, unused sticker sheets, stickered parts, capes, strings, fabric pieces, rubber bands, and cables.

A sticker on the correct element may be worn, misaligned, or damaged. This does not always affect whether the model can be built, but it does affect its collectible condition.

7. Build the model as a final check

An inventory check is faster, but a complete build can be the best final verification. The instructions reveal mistakes that counting alone may miss, such as using a similar part in the wrong place.

A test build is particularly useful when the set contains many similar elements in several shades, parts from different models were mixed together, or you want to confirm that mechanisms work correctly.

How should you record missing parts?

A useful missing-parts list includes the part number, name, color, missing quantity, and total quantity required. A note such as “two white bricks missing” is too vague.

Example: “3005, Brick 1 × 1, white, 2 of 6 pieces missing.” This record lets you find the correct element later without checking the entire set again.

How should you describe completeness when selling?

Use precise wording. A good description might read: “Main-build inventory checked on August 12. One white part 3005 is missing. Minifigures complete. Spare elements were not checked. Instructions included; box missing.”

If you checked the set only by building the model, say so. The buyer will then know that the number of spare parts may not have been verified.

Common mistakes

• Counting a similar color as the correct one. Check shades on a neutral background in daylight.
• Ignoring the part variant. Compare the number and image, not only the general shape.
• Including spares in the main build. Keep the list of additional elements separate.
• Failing to record progress. With several hundred parts, it is easy to forget which entries have already been checked.

Quick checklist

• I have the exact set number.
• I opened the correct parts inventory.
• I separated the spare parts.
• I sorted the elements before counting.
• I checked the part number, color, and quantity.
• I verified the minifigures, printed parts, and stickers.
• I recorded missing items unambiguously.
• I described the instructions, box, and spares separately.

Check a set in BricksIndex

Search for the set number, open its inventory, and begin with the largest elements. If you have a larger collection, create a warehouse and record checked parts together with their storage locations. This means your next completeness check will not have to start from zero.

Check the inventory of a selected set

If you are only beginning to organize your collection, see our guide on how to organize a LEGO collection with BricksIndex.