Ad networks match and rank your products by their identifiers — GTIN (barcode), brand, and MPN — so missing ones cost you reach. Add them three ways: map an identifier column your feed already carries, set the brand with a rule when it's constant, or pull a GTIN in from a supplier feed with a lookup.
Why product identifiers matter#
Product identifiers are how an ad network recognizes which product you're advertising. When Google, Meta, or TikTok can match your product to the same item elsewhere, your listing can carry the right details, show for the right searches, and compete properly — so identifiers directly affect whether a product is eligible to deliver and how far it reaches.
There are three that matter, and they work together:
- GTIN — the barcode number printed on the packaging (you may know it as an EAN or a UPC). It's the strongest identifier because it points at one exact manufactured product.
- Brand — who makes the product. Almost every product should have one.
- MPN — the manufacturer part number, the maker's own code for the item.
The common rule — closest to how Google states it — is: if a product has a GTIN, provide it; if it genuinely doesn't, provide the brand plus MPN together instead [VERIFY: exact identifier-fallback requirement per network]. Some categories — custom-made, handmade, vintage, or your own-brand products with no assigned barcode — are exempt from needing a GTIN at all. The exact exempt categories and the setting used to declare that no barcode exists live in each network's own policy: [VERIFY: Google Merchant Center identifier-exemption categories and the "identifier exists" setting] and [VERIFY: Meta and TikTok identifier requirements].
One thing to know up front: identifiers are recommended, not required, in Renable's mapping. Renable's seven required fields (ID, title, description, URL, main image, price, availability) don't include GTIN, brand, or MPN, so a catalog won't flag them as missing — but the ad network still limits reach for products without them. For the difference, see Required vs. recommended feed fields. For the identifiers themselves in more depth, see Product identifiers: GTIN, brand, and MPN.
Route 1: Map an identifier column you already have#
If your feed already contains a barcode, brand, or part-number column, the fix is just to point the matching catalog field at it. The identifier fields live in the Identity group on the Mapping tab.
- Open the catalog and go to the Mapping tab.
- In the Identity group, find the identifier field you're filling — the GTIN, brand, or MPN field.
- Drag the matching column from the Feed columns rail onto that field's row.
- Check the field's live sample shows the value you expect, then Publish.
The Fill column tells you how much of your catalog the mapping actually covers — a brand field at 100% fill has a value for every product; 70% means three in ten are still blank. The full mechanics of mapping, fallbacks, and reading Fill are in Mapping your feed fields.
Route 2: Set the brand with a rule#
When a brand column doesn't exist in your feed, a rule fills it. This is the go-to for two common cases:
- A single-brand store. Every product is the same brand, so a rule with no conditions (it runs for every product) sets the brand field to a fixed value.
- A derivable brand. The brand can be worked out from another column or a pattern in the data — for example, every product whose type contains a certain word belongs to a known brand. A condition selects that group, and a Set field action writes the brand.
Both are the same shape: a condition (or none) plus a Set field action on the brand field. The full operator list, actions, and value steps are in Fixing your feed data with rules; aiming one rule at a whole category or group is covered in Bulk-fix a whole category with one rule.
The same approach fills a constant MPN prefix or normalizes a messy brand column — add value steps to a Set field action to trim, re-case, or replace text as you write it.
Route 3: Pull a GTIN from a supplier feed with a lookup#
Sometimes your main feed simply doesn't carry barcodes, but a supplier or manufacturer feed does. A lookup joins the two feeds on a shared value and brings the GTIN across.
- On the Data sources tab, add the supplier feed as an Auxiliary feed.
- Open the GTIN field's value (on the Mapping tab, or in a Set field action) and add a lookup.
- Match the two feeds on a column they share — usually a SKU, or brand and MPN together when no single column is unique.
- Set the Return column to the supplier feed's GTIN column, then Publish.
If the column you're matching on is itself a barcode, switch that match pair to Barcode mode so a leading zero doesn't cause a miss. The full lookup setup — match pairs, matching modes, and stacking one lookup as another's fallback to try more than one key — is in Joining another feed.
After you add barcodes: the check-digit check#
The barcode you add gets validated: every GTIN, EAN, and UPC ends in a check digit that has to be consistent with the rest of the number, so a typo or a truncated value produces an invalid barcode. It still imports, but that specific barcode is dropped before the feed reaches any ad network. Feed runs, warnings, and tracing a value owns the detail — how to spot these and fix them.
Your changes aren't live until you Publish#
All three routes save to a draft, and nothing reaches your ads until you Publish. Because imports run your last published configuration, publish before you expect to see new identifiers flow through. The draft-and-publish model is covered in Transforming your feed.
FAQ#
My products don't have barcodes at all — what do I use?
Provide the brand and MPN together; most ad networks accept that pairing as the identifier for products that lack a GTIN [VERIFY: exact identifier-fallback requirement per network]. For genuinely barcode-less products — custom-made, handmade, vintage, or your own brand — networks let you declare that no identifier exists rather than inventing one. The exact categories and how to declare it are the network's own policy: [VERIFY: Google Merchant Center identifier-exemption categories and the "identifier exists" setting].
I added GTINs but the ad network still rejects them — why?
The most common cause is a barcode that fails its check digit — a typo or a value cut short in your feed. See Feed runs, warnings, and tracing a value to find and fix them.
Do I need all three of GTIN, brand, and MPN?
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. Exact per-network and per-category requirements vary — [VERIFY: Google, Meta, and TikTok identifier requirements by category].
Will Renable stop a product for a missing identifier?
No. Identifiers are recommended, not among Renable's seven required fields, so a catalog won't block or flag a product for a missing GTIN, brand, or MPN. The ad network is what limits that product's reach. See Required vs. recommended feed fields.
Or ask Aimée#
You don't have to wire this up by hand. Tell Aimée what you need — "map the barcode column to GTIN," "set the brand to Acme for every product," or "pull GTINs from my supplier feed and match on SKU" — and she can set the mapping, build the rule, add the auxiliary feed and lookup, test that it matches before saving, and publish once you approve.
Where to go next#
- Mapping your feed fields — map an identifier column your feed already has.
- Fixing your feed data with rules — set a brand or MPN with a rule.
- Joining another feed — pull a GTIN in from a supplier feed with a lookup.
- Product identifiers: GTIN, brand, and MPN — what each identifier is and when networks need it.
- Feed runs, warnings, and tracing a value — the barcode check-digit check.