GTIN, MPN and brand: the product identifiers your feed needs, and what to send when a product has none

Merchant Center says a few hundred of your products are missing identifiers. Meta wants a brand on every item. Your supplier’s spreadsheet has a column called EAN, another called MPN, and a third that is empty for everything you make yourself.

Here is what each code does, which network insists on which, what to send for a product that has no barcode, and how to fill the gaps across a whole catalog in one afternoon.

What the three identifiers are

• GTIN is the barcode. The number printed on the packaging. In Europe you know it as the EAN, in North America as the UPC, on books as the ISBN. It names one exact manufactured product, the same everywhere it is sold.
• Brand is who makes it. The label the product is sold under. Nearly every product has one, and it is the identifier networks lean on when there is no barcode.
• MPN is the maker’s own part number. On its own it is not unique across the market. Paired with the brand it names a specific product, which is why the two travel together.

A fourth code often gets mixed in. item_group_id is not an identifier for one product. It is the shared value that tells a network your medium, large and extra large are one product with options. Each size keeps its own ID and its own barcode.

Why a network cares

An ad network uses identifiers to work out which product you are advertising and to match it to the same item in other shops. A product it can identify can show for the right searches and compete with the other listings of that item. A product it cannot identify is harder to place and tends to reach fewer people. Google says it plainly: a product submitted without the GTIN it has may have limited visibility.

The price comparison sites are the sharpest case. Prisjakt lists your offer on the product page other shops are already on, and the barcode is how it finds that page. A missing GTIN there is an offer Prisjakt has to match some other way.

GTIN vs MPN: which one does each network want?

The rule is the same everywhere, worded a little differently.

• Google recommends a GTIN for every product that has one, requires an MPN for products without a manufacturer-assigned GTIN, and requires a brand on new products with a clearly associated brand. So a product without a barcode needs brand plus MPN together.
• Meta requires a brand on every product. GTIN and MPN are optional.
• TikTok requires a brand on every product too.
• Criteo asks for a barcode or a manufacturer part number on every product. One of the two.

So the short answer to “GTIN or MPN?” is: send the GTIN whenever the product has one, and send brand plus MPN when it does not. Set the brand on everything regardless.

What to send when a product has no barcode

Some products genuinely have none. Custom-made and made-to-order goods, handmade items, vintage and antique pieces, and your own-brand products that were never assigned a barcode. Do not invent one. A made-up number either fails validation or points at someone else’s product.

For Google, send brand plus MPN if you have them. For a product with neither, set identifier_exists to no. That tells Google the product is one of the exempt kinds, and Google stops asking. Do not set it on products that do have identifiers. Google warns about that too. Meta and TikTok have no equivalent switch. A correct brand covers what they ask for.

The two ways a barcode you did send still fails

1. The check digit does not add up. Every GTIN, EAN and UPC ends in a digit calculated from the rest of the number. A typo or a value cut short produces a barcode that looks fine and is invalid. Google reports it as an invalid value. Renable catches this one before Google sees it: the product imports, but the bad barcode is dropped before the feed reaches any network, and the import warns you how many were dropped.
2. The number is valid and belongs to another product. Usually a barcode copied from a neighbouring row. Google calls this an incorrect GTIN. No tool can spot it from the number alone. Check the physical product or the manufacturer’s record.

Fill the gaps across the whole catalog, not product by product

Renable imports the feed your store already exports and lets you fix it without touching the store. Identifiers sit in the Identity group of a catalog’s mapping, and there are three ways to fill them.

• Map a column you already have. If the feed carries the barcode under EAN, UPC or Barcode, point the GTIN field at it. The fill bar tells you how much of the catalog that covers.
• Set it with a rule. A single-brand store sets the brand once for every product. A brand that can be worked out from another column gets a rule with a condition. The same rule trims, re-cases or cleans a messy brand column as it writes it.
• Pull it in from a supplier feed. When your feed has no barcodes but the supplier’s does, a lookup joins the two on a SKU, or on brand plus MPN, and brings the GTIN across. Match in barcode mode so a leading zero does not cause a miss. A live counter shows how many sampled products matched before you save, and a second lookup can sit behind the first as a fallback.

All three are drafts until you publish. Then every import keeps them applied, so a new product arrives with its identifiers filled.

Or describe the job to Aimée, the AI agent inside Renable.

One thing to know. Renable marks identifiers as recommended, not required, so a catalog will not block a product for a missing GTIN. The network is what limits that product’s reach. The step-by-step for all three routes is in the help center: Add missing GTINs, brands and identifiers. Variants and out-of-stock products in Meta catalog ads: the three symptoms and the fix for each