GTIN, MPN and Brand: What Shopify Merchants Must Fill In
Where GTIN, MPN and brand come from in Shopify, why Google needs them, and how to fix products with none.
Written by Mantas Jurgutis — Founder, Adsify — builds the Google & Meta automation merchants use daily
Editorially reviewed by Adsify Editorial on March 4, 2026 — Reviewed against Shopify, Google Ads and Meta official documentation.
What these three attributes actually do
GTIN, MPN, and brand together let Google match your listing to its product catalog and to identical listings from other retailers. GTIN (Global Trade Item Number) is the barcode-level identifier — UPC in North America, EAN in Europe. MPN (Manufacturer Part Number) is a secondary identifier used when GTIN isn't available, typically for private-label or made-to-order items. Brand is simply the manufacturer or label name. Google uses this trio to build the 'unique product identifiers' it needs for Shopping ads, comparison shopping features, and for surfacing your listing in relevant searches at all — items missing all three are effectively invisible in most Shopping placements.
Where each field lives in Shopify
Brand maps directly from the Vendor field on a Shopify product (Products > [product] > Organization > Vendor). GTIN maps from the Barcode field on each individual variant (Products > [product] > Variants > click a variant > Barcode). Shopify has no native MPN field, so most feed apps read it from a metafield or a custom field you define — check your feed app's mapping settings under something like Products > Feed > Field mapping to see what metafield namespace it expects for MPN.
When you genuinely have no GTIN
Some products — custom-manufactured goods, refurbished items, or certain private-label lines — never receive a GTIN from a manufacturer. In these cases, leaving Barcode blank without any flag causes a 'missing GTIN' disapproval, because Google assumes you simply forgot to enter it. The correct fix is setting the identifier_exists attribute to false in your feed (via your feed app's settings, since Shopify itself doesn't expose this attribute), which tells Google's system that no valid identifier exists rather than that one was omitted.
Bulk-fixing missing values across a catalog
For catalogs with hundreds of SKUs missing Barcode or Vendor, the fastest fix is exporting products to CSV from Shopify admin (Products > Export), filling in the Variant Barcode and Vendor columns from your supplier's data sheet or UPC database, then re-importing via Products > Import. Always import with 'Overwrite existing products' matched by Handle so you update rather than duplicate. Run a small test batch of 5–10 products first to confirm the column mapping is correct before running the full file.
Brand consistency matters beyond just being present
Google flags brand inconsistency too — if the same physical product appears with 'Nike' in one listing and 'nike Inc.' in another (even across different sellers), it can create duplicate-detection confusion that affects how your listing ranks in comparison contexts. Keep Vendor values consistent and exactly matching the manufacturer's registered brand name, not a store-specific label or sub-brand name you use internally.
MPN as a fallback, not a substitute
Don't treat MPN as an equal alternative to GTIN when a real GTIN exists. Google's guidance is to always submit the actual GTIN when one is available, and MPN is only a valid substitute when no manufacturer identifier was ever assigned. Submitting a store-generated SKU number as if it were an MPN will get flagged, because it isn't a manufacturer-issued identifier and won't match anything in Google's product catalog.
Checking your current coverage
In Merchant Center, Products > Diagnostics will show a count of items affected by 'missing or invalid GTIN, MPN, or brand.' Click into that row to get the affected item IDs, cross-reference them against your Shopify product list by handle, and prioritize fixing your highest-revenue or highest-traffic SKUs first if you're working through a large backlog rather than fixing alphabetically.