GTIN and Product Identifiers: The Complete Guide for E-commerce

Product identifiers—GTINs, UPCs, MPNs, and brands—are the unsung heroes of product feed management. These codes help shopping platforms understand exactly what product you're selling, match it against their product database, and present accurate information to shoppers.

Yet product identifiers are also one of the most confusing aspects of feed management. When are they required? What's the difference between a GTIN and a UPC? What do you do when your products don't have them?

This guide demystifies product identifiers and provides practical guidance for handling them in your feeds.

Understanding Product Identifiers

Why Identifiers Matter

Product Matching

Shopping platforms maintain vast databases of products. Identifiers allow them to match your listings against known products, enabling:

• Product reviews to appear on your listings
• Price comparison features
• Accurate product categorization
• Better search relevance

Data Quality

Identifiers help platforms verify your product data is accurate. If your GTIN matches a product but your title doesn't, that's a signal something might be wrong.

Fraud Prevention

Identifiers help prevent counterfeit or misrepresented products from appearing in shopping results.

Performance Impact

Products with valid identifiers often get better visibility and performance. Google has stated that products with identifiers may be eligible for additional features.

The Three Key Identifiers

GTIN (Global Trade Item Number)

The universal product identifier. GTINs come in several formats:

• UPC (12 digits): Universal Product Code, primarily used in North America
• EAN (13 digits): European Article Number, used internationally
• JAN (13 digits): Japanese Article Number, used in Japan
• ISBN (13 digits): International Standard Book Number, used for books
• ITF-14 (14 digits): Used for multipacks and cases

The barcode on product packaging usually contains the GTIN.

MPN (Manufacturer Part Number)

A unique code assigned by the manufacturer to identify a specific product. MPNs are:

• Assigned by the manufacturer (not a global standard)
• Unique within a manufacturer's catalog
• Often found on packaging or in product documentation
• Particularly important for parts, electronics, and industrial products

Brand

The manufacturer or brand name of the product. While it seems simple, brand accuracy matters:

• Use the manufacturer's official brand name
• Don't use your store name unless you manufacture the product
• Spelling must be accurate

GTIN Deep Dive

GTIN Structure

UPC-A (12 digits)

Format: Company Prefix (6-10 digits) + Item Reference (1-5 digits) + Check Digit (1 digit)

Example: 012345678905

EAN-13 (13 digits)

Format: Country Code (2-3 digits) + Company Prefix + Item Reference + Check Digit

Example: 5901234123457

Validating GTINs

GTINs include a check digit that validates the number is correctly formed. The check digit is calculated using a specific algorithm, and if it doesn't match, the GTIN is invalid.

Check Digit Calculation

1. Starting from the right, multiply alternating digits by 1 and 3
2. Sum all the products
3. The check digit is the number needed to round up to the nearest 10

Many online tools can validate GTINs for you.

Where to Find GTINs

Product Packaging

The barcode on the product or packaging contains the GTIN. It's printed below or near the barcode.

Manufacturer Data

Product spec sheets, catalogs, or databases from manufacturers often include GTINs.

Supplier Data

Your supplier or distributor should be able to provide GTINs for products they supply.

GTIN Databases

Several databases can help you look up GTINs:

• Open Food Facts: For food products
• UPCitemdb: General product database
• Barcode Lookup: Consumer product search
• GS1 GTIN Registry: Official registry (limited access)

When GTINs Don't Exist

Not all products have GTINs:

• Custom or handmade products: One-of-a-kind items
• Very old products: Predating barcode standards
• Private label products: Store brands without GTINs
• Services or digital products: Non-physical items
• Parts and components: Industrial items may only have MPNs

Platform Requirements

Google Shopping

When GTINs Are Required

Google requires GTINs for products where they exist and are assigned by the manufacturer. This includes most manufactured consumer goods.

When GTINs Aren't Required

• Custom-made products
• Vintage or antique items
• Products made before GTINs existed
• Some apparel and accessories
• Media (movies, music, video games) where ISBNs/other IDs apply

The identifier_exists Attribute

For products without GTINs, set identifier_exists to "no" or "false". This tells Google the product legitimately doesn't have a GTIN.

Important: Only use identifier_exists="no" when the product genuinely has no identifier. Using it to avoid providing available GTINs can result in disapprovals or account issues.

Google's Identifier Requirements

When GTINs are available:

• Provide the correct GTIN
• Include brand
• MPN is optional but recommended

When GTINs don't exist:

• Set identifier_exists to "no"
• Provide brand (if applicable)
• Provide MPN (if applicable)

Meta (Facebook/Instagram)

Identifier Requirements

Meta strongly recommends GTINs but doesn't strictly require them for all products. However, products with valid identifiers may receive better performance.

Supported Identifiers

• gtin: Primary identifier
• brand: Required for most products
• mpn: Manufacturer part number

Other Platforms

Microsoft/Bing

Similar requirements to Google. GTINs required when they exist; use identifier_exists when they don't.

Pinterest

GTINs recommended but not strictly required. Products with identifiers may get better catalog features.

TikTok Shop

Requires product identifiers where applicable. Check current documentation for specific requirements.

Common Identifier Issues

Invalid GTIN

Causes:

• Typo in the number
• Using an internal SKU instead of GTIN
• Check digit doesn't validate
• Wrong format or length

Solutions:

• Validate GTINs before submission using check digit verification
• Cross-reference with manufacturer data
• Verify the number on actual product packaging

GTIN Mismatch

Causes:

• GTIN from a different product
• Variant GTIN used for parent product
• Old GTIN from discontinued version

Solutions:

• Ensure GTIN matches the exact product and variant
• Update GTINs when products are revised
• Verify against physical product

Brand Mismatch

Causes:

• Store name used instead of manufacturer
• Misspelled brand name
• Retailer brand used for third-party products

Solutions:

• Use manufacturer's official brand name
• Check spelling against official sources
• Only use your brand for products you manufacture

Missing Identifier When Required

Causes:

• GTIN not in your product data
• Supplier didn't provide identifier
• Data import lost identifier values

Solutions:

• Source GTINs from suppliers or manufacturers
• Look up GTINs in barcode databases
• Request identifier data from supply chain

Obtaining GTINs

For Products You Manufacture

If you manufacture products and need GTINs:

1. Join GS1: The organization that manages GTINs
2. Get a company prefix: A unique identifier for your company
3. Assign item numbers: Create unique GTINs for each product
4. Print barcodes: Add barcodes to packaging

GS1 membership has costs that vary by company size and number of products.

For Products You Resell

Products you purchase for resale should already have GTINs:

• Request GTIN data from suppliers
• Scan barcodes from physical products
• Look up products in manufacturer databases
• Use barcode lookup services

Private Label Products

For private label products you develop:

• You'll need to obtain GTINs through GS1
• Some contract manufacturers may provide GTINs
• If no GTIN, use identifier_exists="no"

Identifier Best Practices

Data Quality

Validate Before Submission

• Verify check digits are correct
• Ensure format matches expected length
• Cross-reference with known good data

Match Variants Correctly

• Different variants (colors, sizes) often have different GTINs
• Ensure each variant has its specific identifier
• Parent products may have different identifiers than variants

Keep Data Updated

• Products may get new GTINs when revised
• Update identifiers when products change
• Remove identifiers for discontinued products

Feed Management

Consistent Formatting

• Remove leading zeros consistently (or keep them consistently)
• No spaces, dashes, or other characters in GTIN
• Numeric values only

identifier_exists Usage

• Only set to "no" when product genuinely has no identifier
• Don't use as workaround for missing data
• Default is "yes" if not specified

Supplemental Feeds

Use supplemental feeds to:

• Add identifiers to products missing them
• Correct identifier errors without changing primary feed
• Update identifiers from external data sources

Identifier Lookup Strategies

Building an Identifier Database

1. Collect identifiers from all suppliers
2. Scan barcodes from physical inventory
3. Research missing identifiers in databases
4. Maintain mapping of SKUs to identifiers

Automation

• Integrate with supplier data feeds that include identifiers
• Use barcode scanning for receiving and inventory
• Validate identifiers during product import
• Flag products missing identifiers for review

Ongoing Maintenance

• Review products flagged for identifier issues
• Update identifiers when products change
• Audit identifier accuracy periodically
• Monitor platform diagnostics for identifier errors

Special Cases

Bundles and Multipacks

Bundles of multiple products:

• May have their own GTIN (ITF-14 format)
• Or may need identifier_exists="no"
• Don't use component product GTINs for bundles

Refurbished Products

Refurbished items:

• Use the original product's GTIN
• Set condition to "refurbished"
• Title and description should indicate refurbished status

Books and Media

Special identifier types:

• ISBN: For books (13-digit format)
• ISSN: For periodicals
• UPC: For music, movies, video games

Conclusion

Product identifiers are essential for shopping feed success. They help platforms understand your products, match them to their databases, and present accurate information to shoppers. While managing identifiers can be complex, the effort pays off in better performance and fewer disapprovals.

Focus on obtaining accurate identifiers from your supply chain, validating data before submission, and properly handling products that genuinely lack identifiers. With good identifier hygiene, you'll have healthier feeds and better shopping campaign performance.

GetFeeder includes identifier validation and management features that help ensure your GTINs, MPNs, and brands are correct before submission. Our tools flag potential issues and help you maintain identifier accuracy across your entire catalog.