GTINs and product identifiers
Identifiers are how Google knows that your listing and four competitors’ listings are the same physical product. Get them right and you enter the comparison; get them wrong and you enter the wrong one.
The three identifiers
- GTIN. The global trade item number, or barcode. EAN in Europe, UPC in North America, ISBN for books. Assigned by the manufacturer, globally unique.
- MPN. The manufacturer part number. Unique within a brand, not globally.
- Brand. The brand as buyers know it, which is not always the legal entity name.
What to submit
| Situation | Submit |
|---|---|
| Branded product with a barcode | GTIN, brand, and MPN if known |
| Branded product with no GTIN | Brand and MPN, identifier_exists false |
| Your own private label | Brand and MPN; a GTIN if you have registered one |
| Handmade or one-off | Brand and MPN, identifier_exists false |
| Books, film, music | ISBN or the relevant GTIN, which almost always exists |
What a wrong GTIN costs
More than a missing one. A wrong GTIN maps your listing onto a different product: your item appears in comparisons for something it is not, against prices it cannot match, and shoppers who click bounce. Google increasingly validates GTINs against manufacturer data and will disapprove ones that do not check out.
The most common source of wrong GTINs is a supplier spreadsheet where the column was truncated, the check digit was dropped, or a leading zero was eaten by a spreadsheet application. Validate check digits on import.
Why a correct GTIN is worth having
- It puts you into the product comparison, which is where a lot of Shopping traffic actually converts.
- It lets Google enrich your listing with manufacturer data you did not supply.
- It improves matching for queries that name a model rather than a category.
- It is increasingly what AI shopping surfaces use to identify a product across retailers.
identifier_exists
Set it to false only when the product genuinely has no manufacturer identifier: custom, handmade, vintage, or your own unbarcoded private label. Using it to silence a warning on products that do have GTINs is a short-term fix that costs you the comparison placements permanently.