Google Merchant Center Unique Product Identifiers: GTINs, MPNs, and Brand

Published: 2026-06-09

What Are Unique Product Identifiers

Google Shopping uses unique product identifiers (UPIs) to match your products to the right searches and to prevent duplicate listings. The three types are GTIN (Global Trade Item Number), MPN (Manufacturer Part Number), and Brand. Together they tell Google exactly what product you are selling.

GTIN: The Most Important Identifier

A GTIN is the barcode number on most commercially produced products. For products sold in retail stores, the GTIN is the UPC (12 digits in North America) or EAN (13 digits in Europe). GTINs are assigned by GS1, the global standards organization. If your product has a barcode on its packaging, submit that barcode as the GTIN. Incorrect GTINs cause item disapprovals. Missing GTINs on products that have them cause warnings and can reduce visibility in Shopping results.

When GTINs Are Required

Google requires GTINs for all products that have been assigned a GTIN by the manufacturer. This covers almost all branded consumer goods. The exceptions are custom products, handmade items, one-of-a-kind pieces, and certain apparel categories that use internal SKUs instead of universal barcodes. If your product has a barcode, use it. Do not invent or reuse GTINs.

MPN: For Products Without GTINs

For products without a GTIN, such as custom-manufactured parts, accessories, or industrial components, submit the MPN (Manufacturer Part Number) instead. The MPN is the part number the manufacturer uses internally. Combined with brand, it creates a unique identifier that Google can use to resolve the product. If neither GTIN nor MPN applies, set the identifier_exists attribute to false.

identifier_exists: How to Handle Truly Unique Products

If you sell handmade, vintage, or one-of-a-kind products that have no standard identifiers, set identifier_exists to false in your feed. This tells Google you are not supplying identifiers because none exist, not because you forgot. Submitting identifier_exists false incorrectly for branded products that do have GTINs causes policy violations and item disapprovals.

Common Errors and Fixes

The most common UPI errors are: submitting an incorrect GTIN (check the barcode on the physical product), submitting a GTIN with a wrong check digit (use GS1's GTIN validation tool), reusing the same GTIN for different variants (each variant needs its own GTIN), and missing brand when submitting an MPN (brand plus MPN together form the identifier pair). For each error, fix the feed value and resubmit.