GTIN, brand, and MPN: getting Google’s product identifiers right

Google uses identifiers to recognise that your product is the same one sold elsewhere, so it can group offers, show the right details, and rank your listing against competitors. A GTIN, the number behind a UPC, EAN, or ISBN barcode, is the strongest signal: it points at one exact manufactured product. Brand and MPN (manufacturer part number) do similar work when a GTIN does not exist. When these are missing, wrong, or invented, Google cannot trust what the product is, and that uncertainty shows up as a disapproval or a demoted listing.

• GTIN: the number behind a UPC, EAN, or ISBN barcode, the strongest identifier.
• Brand and MPN: identify the maker and the specific model when there is no GTIN.
• Missing or wrong identifiers make Google unsure what the product is, and it demotes or disapproves it.

If you sell products made by someone else that carry a manufacturer barcode, most branded retail goods, Google expects the GTIN, and leaving it out or faking it causes problems. If you make your own products, sell handmade or vintage items, or carry own-brand goods that were never assigned a GTIN, there is a correct way to say so: mark that the identifier does not exist and provide brand and MPN instead. The mistake is inventing a GTIN to fill the field, or omitting identifiers entirely without telling Google the product genuinely has none.

• Branded goods with a manufacturer barcode: provide the real GTIN.
• Handmade, vintage, custom, or own-brand without a GTIN: declare no identifier exists, then give brand and MPN.
• Never invent a GTIN, and never leave the fields blank without signalling the product has none.

A few patterns account for most identifier issues. An invalid GTIN, wrong length, failed checksum, or a number that belongs to a different product, reads as a data error. A missing brand on a product that clearly has one looks like a thin listing. A made-up or reused GTIN can trip Google’s validation against the global registry. And declaring that no identifier exists on a product that plainly does, a branded item with a barcode, contradicts what Google can see, which is its own kind of red flag.

• Invalid GTIN: wrong length, bad checksum, or belongs to another product.
• Missing brand on a product that clearly has one.
• Invented or reused GTINs that fail Google’s registry check.
• Claiming no identifier exists on a product that obviously has one.

Because identifiers describe what the product is, the fix belongs in the product data itself, not in a patch on top of the feed. Put the real GTIN on branded items, keep the brand name consistent with how the manufacturer writes it, and use the MPN that matches the exact model. For products that genuinely have no GTIN, set the no-identifier signal deliberately and pair it with brand and MPN so the listing still stands on its own. Then confirm the corrected values are the ones actually reaching Merchant Center, since a fix that never syncs is not a fix.

• Put the real GTIN on branded products; do not fabricate one.
• Keep brand spelled the way the manufacturer writes it, consistently across variants.
• For no-GTIN products, set the no-identifier flag and provide brand and MPN.
• Confirm the corrected values actually reach Merchant Center, not just your store admin.

Identifiers drift as catalogs grow: a new supplier feed arrives without GTINs, a bulk edit blanks a brand, a variant inherits the wrong part number. Any of these can quietly disapprove a slice of your catalog while the rest looks healthy. The stores that stay clean check identifier health on a schedule instead of waiting for a traffic drop to reveal it. A regular scan that reads the live status of each product flags the new gaps early, while they are a handful of fields to fix and not a pile of hidden disapprovals. It is an informational check, not legal advice, and it does not guarantee compliance, but catching a bad identifier before Google does keeps the product selling.