How much is my LEGO set worth

A second-hand LEGO set is worth what buyers have recently paid for that set number, in the same condition, in the UK. It is not the original shop price, and it is not the highest asking price still sitting unsold. Retired sets can sell for more than they cost new. Sets that are still on sale in the shops usually sell for less than the current retail price, because the buyer can still buy one sealed.

On Brick Deals, start with the checker on the homepage. Search the set name or the set number. Say whether the box is unopened or opened, then choose Pristine, Good, or Poor. The estimate uses recent resale prices and then adjusts them for that condition. It is a guide for your listing, not a promise that a buyer will pay the top of the range. You set the final price yourself when you start selling.

The set number is the reliable name. It looks like 75192 or 10294-1. You will find it on the front of the box, on the back near the barcode, and on the instructions. A theme name such as Star Wars is not enough, because that theme has hundreds of sets at very different prices. If the box and the booklet are both gone, search the set name and compare the model with photos in the catalogue.

If a search finds nothing, try the number without a hyphen, or the name of the set as printed on the box. Some sets were sold as a base set plus an extra. The number on the instructions is the one buyers search for. Write that number in the listing title so the set can be found.

Condition is the main difference between two copies of the same set. A sealed box with no dents is at the top. An opened box with every bag still sealed is next. A built set with every part, the instructions, and the box is still a strong sale. The same set without the box is worth less, but it is not worthless. Missing parts, especially a minifigure, move the price down again. Yellowed bricks, cracked pieces, chewed parts, and sun-faded boxes should be priced as poor, not as pristine.

Stickers and printed parts matter. A set with stickers still on the sheet is easier to sell than one with creased stickers already applied badly. Instructions with torn pages are worth mentioning. The box itself is part of the product for sealed sets: a crushed corner is damage, not just packaging. For a used set, the box is helpful but the parts and minifigures decide the price. Read selling without the box and incomplete sets if that is what you have.

Themes that collectors follow, including Star Wars, Technic, and modular-style buildings, are easier to price because there are more recent sales. A small City set from a few years ago may only be worth the minifigures. When the estimate looks wrong, look at live listings and at what you would pay yourself. Then list at a price you would accept, not at a price you hope someone panics into.

• Compare like with like. A sealed price is not a price for a built set.
• Ignore a single very high or very low sale unless you know why it happened.
• Remember postage. A large set costs more to post, and buyers notice the total.
• You keep the item price on Brick Deals. The buyer pays the 5% protection fee and postage on top. See fees.
• If the set is still in the shops, check today's retail price before you list above it.