Submitting GTINs for Google Merchant Center

When submitting product data to Google Merchant Center (GMC), providing accurate Global Trade Item Numbers (GTINs) is essential for product approval and optimal performance across Google surfaces. Incorrect or missing GTINs may lead to product disapprovals, reduced visibility, and lower ad effectiveness.

This article explains what GTINs are, how SHOPLINE submits GTINs to GMC, the correct formatting requirements, and how to resolve common GTIN-related errors. Follow these guidelines to ensure that your products are correctly identified by Google and can be successfully listed and advertised.

Introduction to GTIN

A Global Trade Item Number (GTIN) is a globally recognized product identifier assigned by a manufacturer. Google uses the gtin attribute to match and classify products across Google Shopping and other Google surfaces. Supplying the correct GTIN helps Google understand your products, improves visibility, and enhances ad performance.

If a product has a manufacturer-assigned GTIN, you must submit it. If the product does not have a GTIN, you should instead provide brand + MPN or indicate that no identifiers exist. For more details, see the "GTIN Formatting Guidelines" section.

Entering GTIN in SHOPLINE

For SHOPLINE stores connected to Google Merchant Center, the value entered in the Barcode field on the product details page is used as the GTIN when generating product data for GMC. Follow the steps below to set it up:

1. In your SHOPLINE admin, go to Products and open the product you want to edit.

2. On the product details page, locate the Barcode (ISBN, UPC, GTIN, etc.) field and enter the exact GTIN assigned by the manufacturer.

   

3. Click Update to save the settings.
4. Repeat the steps for all products that have a manufacturer-assigned GTIN.

Once saved, SHOPLINE will use the value in the Barcode field as the GTIN when generating and syncing product data to Google Merchant Center.

GTIN Formatting Guidelines

Google accepts several types of GTIN formats under the gtin attribute:

Important Notes

• Only submit a GTIN if you are certain it is correct. Google explicitly warns not to guess or fabricate GTIN values.
• If the product has a manufacturer-assigned GTIN, you must provide it.
• If the product does not have a GTIN (e.g., handmade, custom/private-label, unique in-house products):
  • Provide brand + MPN, or
  • Set identifier_exists = false 
• Products submitted with incorrect GTINs may be disapproved or perform poorly due to incorrect matching.
• Each variant (size, color, etc.) must have its own unique GTIN. 

Troubleshooting GTIN Errors

This section outlines common GTIN errors in Google Merchant Center and how to resolve them to ensure your product identifiers are correctly recognized by Google.

Determine Whether the Product Has a GTIN

Before checking whether a GTIN is correct, first confirm whether the product is expected to have one.

Products that should have a GTIN:

• Mass-produced branded retail products: You must submit the correct manufacturer-assigned GTIN.

Products that might not have a GTIN:

• Custom-made or handmade items
• Private-label or small-batch items
• Merchant-created bundles or sets
• Vintage or one-of-a-kind items

Verify the Accuracy of the GTIN

If the product should have a GTIN, verify that the submitted value is correct:

• Compare the GTIN with the barcode on the product or packaging.
• Ensure the GTIN has the correct number of digits and a valid check digit.
• If unsure, verify the GTIN with the manufacturer or supplier.

Incorrect or mismatched GTINs are the most common cause of errors, such as "Invalid GTIN  or "GTIN Not Recognized" in Merchant Center.

Provide Alternative Identifiers If No GTIN Exists

If the product genuinely does not have a manufacturer-assigned GTIN:

• Provide a valid brand and MPN, or
• Set identifier_exists = false to indicate that no identifiers are available.

This prevents GTIN-related disapprovals for products that are not required to have them.

Contact Google Merchant Center Support

If your GTIN is correct but still triggers errors:

1. Open GMC > Products > Diagnostics to review item-level error details.
2. Contact Google Merchant Center Support for assistance.

Google can help diagnose issues related to restricted prefixes, uniqueness conflicts, or feed formatting problems.