LEGO price guide: how BrickIndex estimates value

Start with sold prices

BrickIndex uses available BrickLink sold-price data to estimate the value of minifigures and sets in US dollars. An asking price shows what a seller hopes to receive. A completed sale provides a different reference: a price someone actually paid.

We show used and new estimates separately. These are historical reference values. BrickIndex does not offer the catalog item for sale, guarantee a sale price, or authenticate a particular copy.

How the calculation works

1. Match the catalog item to its BrickLink identifier and condition category.
2. Use the available six-month sold-price history.
3. When individual sale records are available, calculate their median price, then exclude records below one tenth or above ten times that median.
4. Calculate a quantity-weighted median from the remaining records. A transaction for several units receives more weight than a single-unit sale.
5. If individual records are unavailable, use the quantity-weighted average supplied by the source when available.

The wide outlier filter removes extreme records; it cannot detect every mismatch, incomplete item or unusual sale. A thin sales history can still produce an uncertain estimate.

How fresh are the values?

Prices are cached to keep the app responsive and limit upstream requests. The normal cache window is six hours, but request budgets or an unavailable source can cause an older cached value to be shown. A page visit does not guarantee a fresh market lookup. If there is no usable estimate, the catalog displays “Not available.” That does not mean the item is worth zero.

What the estimate cannot see

Cracks, worn printing, discoloration, replacement parts, missing accessories, box condition, shipping costs and seller location can all affect a real transaction. Match the exact variant before comparing prices, and compare complete copies with complete copies.

For sets, check whether the minifigures, instructions and box are included. For a minifigure, compare its component combination as carefully as its character name.

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