Product Identifiers: GTIN, Brand, and MPN

Product identifiers are the standard codes that tell an ad network exactly which product you're advertising: a GTIN (the barcode — EAN, UPC, or ISBN), the brand that makes it, and the MPN (the manufacturer's part number). Networks use them to match your product to the same item elsewhere and rank it, so missing ones cost you reach.

What each product identifier is#

The three identifiers work together, from most specific to least:

GTIN — the barcode#

A GTIN (Global Trade Item Number) is the barcode number printed on a product's packaging. You'll usually know it by its regional name — an EAN in Europe, a UPC in North America, or an ISBN on books. It's the strongest identifier because it points at one exact manufactured product, the same everywhere it's sold.

Brand — who makes the product#

The brand is the maker or label the product is sold under. Almost every product has one, and it's the identifier ad networks lean on when there's no barcode.

MPN — the manufacturer's part number#

The MPN (manufacturer part number) is the maker's own internal code for the item. On its own it isn't unique across the market, but paired with the brand it names a specific product — which is why the two are quoted together as a fallback when a barcode is missing.

Why ad networks use product identifiers#

Ad networks like Google, Meta, and TikTok use identifiers to recognize which product you're advertising and connect it to the same item across the web. That matching does two things for you:

• It makes your product eligible. When a network can confidently identify your product, your listing can carry the right details and show for the right searches. A product it can't identify is harder to place — and often reaches fewer people.
• It helps your product compete. Once a network can match your item to the same product elsewhere, it can rank and surface it properly against competing listings. Good identifiers put your product in that competition; missing ones leave it out.

In short: identifiers are how a network trusts what your product is. The better it can identify a product, the further that product tends to reach.

When product identifiers are required — and when they're exempt#

The general rule — closest to how Google states it — is straightforward: if a product has a GTIN, provide it; if it genuinely doesn't, provide the brand plus MPN together instead. Google recommends a GTIN for every product that has one, requires an MPN for products without a manufacturer-assigned GTIN, and requires a brand for new products with a clearly associated brand. Meta requires a brand on every product, with GTIN and MPN optional, and TikTok requires a brand on every product too.

Some products genuinely have no barcode, and networks don't expect you to invent one:

• Custom-made, handmade, or made-to-order products.
• Vintage, antique, or one-of-a-kind items.
• Your own-brand products that were never assigned a manufacturer barcode.

For those, you leave the GTIN out rather than inventing one. When a product has no GTIN and no brand-plus-MPN either — Google's examples are custom goods, one-of-a-kind and handmade items, vintage goods, antiques, and books published before 1970 — you tell Google by setting the identifier_exists attribute to no. Don't set it on products that do have identifiers; Google warns about that. Meta and TikTok don't document a separate setting for this; a correct brand covers what they ask for.

One thing that surprises people: a well-formed barcode can still be wrong. Every GTIN, EAN, and UPC ends in a check digit calculated from the rest of the number, so a typo or a truncated value produces an invalid barcode. On top of that, Google raises an issue for a correctly formatted barcode that belongs to a different product — its Incorrect GTIN issue, often caused by a barcode copied from another item. A structurally valid barcode that names the wrong product still gets reported.

Are identifiers required in Renable?#

No — and this is worth knowing. Identifiers are recommended, not required in a catalog. Renable's seven required fields are ID, title, description, URL, main image, price, and availability, so a catalog won't call out a product as missing a GTIN, brand, or MPN. The ad network is what limits reach for products without them, not Renable. This is why a product can pass every check in Renable and still under-deliver on Google or Meta for a missing identifier.

How you add and fix identifiers in Renable#

Identifiers live in the Identity group on a catalog's Mapping tab, and there are three ways to fill them:

• Map a column you already have — if your feed carries a barcode, brand, or part-number column, point the matching catalog field at it on the Mapping tab.
• Set a value with a rule — when a value is constant or derivable (a single-brand store, a fixed MPN prefix), a Set field rule writes it.
• Pull one in from another feed — when your main feed lacks barcodes but a supplier feed has them, a lookup joins the two feeds and brings the GTIN across.

The full step-by-step for all three is in Add missing product identifiers — this glossary entry explains what the identifiers are; that article covers how to fill them.

FAQ#

My products don't have barcodes — what do I use instead of a GTIN?

Provide the brand and MPN together. That's what Google asks for when a product has no manufacturer-assigned GTIN. Meta and TikTok both require a brand. For products that have no identifiers at all — custom-made, handmade, one-of-a-kind, or vintage goods — don't invent one: on Google, set identifier_exists to no instead.

Do I need all three of GTIN, brand, and MPN on every product?

Generally you provide a GTIN whenever the product has one, and fall back to brand plus MPN when it doesn't. Brand is worth setting on nearly every product regardless. The exact requirement differs by network: Google wants the GTIN where one exists and brand plus MPN where it doesn't, while Meta and TikTok both require a brand.

I added a GTIN but the ad network still rejects it — why?

Two common causes. First, a barcode whose check digit doesn't add up — a typo or a value cut short — imports but is dropped before your feed reaches any ad network, so it arrives as missing. Second, a well-formed barcode that doesn't match the product the network has on record. See Fix products disapproved by Google.