What Is a GTIN? Meaning, Types and Google Rules

What is a GTIN?

A GTIN is the number printed under a product's barcode. It identifies one exact product, in one size and one color, everywhere in the world. GTIN stands for Global Trade Item Number, and GS1, the global standards body behind barcodes, is the only organization that issues them.

The GTIN is the number. The barcode is the black and white bars that let a scanner read it. GS1 US explains that a GTIN has two jobs. In a physical store, the barcode is scanned at checkout. Online, the GTIN makes sure the item you list is the item that gets picked, packed and shipped. Marketplaces and Google also use it as a key to pull up everything else they know about that product.

Because the brand owner assigns the GTIN, every store that sells the same product submits the same number. That is what makes it useful to Google: when 40 stores sell the same blender, the shared GTIN tells Google it is one product with 40 offers, not 40 different blenders.

GS1 licenseThe brand owner licenses a single GTIN or a company prefix

GTIN assignedOne number per product, size and color

Barcode printedA UPC-A barcode carries a 12-digit GTIN in the US

Feed attributeThe store sends it in the gtin field to Merchant Center

Product matchedGoogle links the offer to the right product and searches

What are the types of GTIN?

There are four GTIN lengths: GTIN-8, GTIN-12, GTIN-13 and GTIN-14. Most US products carry a GTIN-12, better known as the UPC. Products made for Europe and most other countries carry a GTIN-13, called an EAN. Books use a 13-digit ISBN, which is also a GTIN-13.

The type rows and digit counts come from GS1 US and GS1 Support; the Merchant Center notes come from Google's gtin attribute page.

How is a GTIN built?

Every GTIN has three parts: a GS1 Company Prefix licensed to the brand, an item reference the brand picks for each product, and a check digit at the end. A GTIN-14 adds an indicator digit at the front. Digits 1 to 8 mark a packaging level, such as a case of 12, and 9 marks a variable measure item, per the GS1 US GTIN guideline.

The check digit catches typos. If one digit is wrong or two digits are swapped, the math no longer adds up, and Merchant Center flags the value as invalid.

Here is GS1's method applied to the sample GTIN-13 that Google uses in its own help pages, 3234567890126:

1. Take every digit except the last. 3 2 3 4 5 6 7 8 9 0 1 2.
2. Multiply from the right by 3, then 1, then 3, and so on. Left to right that gives 3, 6, 3, 12, 5, 18, 7, 24, 9, 0, 1, 6.
3. Add the results. The sum is 94.
4. Subtract from the next multiple of ten. 100 minus 94 is 6, which matches the last digit of 3234567890126.

You rarely need to do this by hand. GS1 has a free check digit calculator. The point is simpler: a number that fails this test is not a GTIN, and a number that passes it can still belong to someone else.

GTIN vs UPC vs EAN vs SKU vs MPN: what is the difference?

GTIN is the umbrella name. A UPC is a 12-digit GTIN and an EAN is a 13-digit GTIN, so both are GTINs. A SKU is your own stock code, and an MPN is the manufacturer's part number. Neither a SKU nor an MPN is a GTIN.

One mix-up is easy to make: an internal SKU in the gtin field. Google's unique product identifier guidance says not to put internal SKUs or other store-specific values in gtin, brand or mpn. Ten stores selling the same product share one GTIN, but each has its own SKU.

GTIN (global)

• Issued through GS1 to the brand owner
• Same number at every store that sells the product
• Printed under the barcode
• Lets Google match your offer to the product

SKU (internal)

• Made up by you
• Different at every store
• Lives in your inventory system
• Belongs in id, never in gtin

JAN codes follow the same logic: a JAN is the Japanese name for a GTIN-13 (or GTIN-8), so it goes in the gtin field too.

How do you get a GTIN for your products?

If you resell another company's products, you don't buy GTINs. You copy the manufacturer's number from the packaging or ask the supplier. If you own the brand, you license GTINs from GS1, which is the only legitimate source. GS1 Support states that only GS1 can provide a GS1 GTIN and that you get one by joining your local GS1 Member Organization, which in the US is GS1 US.

1. Count your variants. Every size, color, scent and pack size is its own product. GS1 US uses the example of a t-shirt in 3 sizes and 3 colors: 9 products, so 9 GTINs.
2. Pick a license. A single GS1 US GTIN suits a few products. A GS1 Company Prefix suits a growing line, because it covers a block of numbers.
3. Check out on the GS1 US store. GS1 US says a welcome email arrives within minutes, and both options include its Data Hub tool.
4. Assign and print. Use Data Hub to assign each GTIN to a product and create the barcode artwork.
5. Add the numbers to your store and feed. Put each GTIN on the matching variant, as shown in the platform section below.

As of October 2026, GS1 US lists these prices on its barcode pricing page. GS1 US can change them at any time.

Single GTINs can't be used for pharmaceutical products, variable measure items, mixed cases or coupons. For those you need a prefix.

Why cheap resold barcodes fail

Barcode resellers sell numbers that GS1 first licensed to some other company. GS1 states that it never issues the same GTIN twice and does not allow GTINs to be transferred or resold. On its selling online page, GS1 explains that a resold number shows up in its public database with the data of the company that first licensed it, not yours.

That causes two problems. If the number was ever used on another product, Google sees a GTIN that belongs to something else and flags it as an Incorrect GTIN, which leads to disapproval. And anyone can look the number up in the GS1 Company Database, where it points to a company that isn't you. Amazon goes further: GS1 US quotes Seller Central saying Amazon checks UPCs against the GS1 database and treats non-matching ones as invalid.

Does Google Merchant Center require a GTIN?

Yes, for any product that has a GTIN assigned by its manufacturer. Google calls the gtin attribute strongly recommended, and says products sent without an identifier they have may get limited performance or be disapproved. Products that never had a GTIN don't need one. For those, you send brand plus MPN, or set identifier_exists to no.

What Google won't accept is a guess. Its product data specification says a product with an incorrect GTIN will be disapproved, and its gtin page says "When in doubt don't provide a GTIN." So when you are unsure, blank beats wrong.

The table follows Google's pages on unique product identifiers, MPN and identifier_exists. A few details matter. Used and vintage goods should keep their original GTIN when it exists, with condition set to used. A product you customize, such as an engraved watch, keeps the manufacturer's GTIN. Google also lists replacement parts, OEM parts and pre-order products as items that may lack a GTIN.

When should you set identifier_exists to no?

Set it to no only for new products that have no manufacturer-assigned identifiers: custom goods, handmade items, art, vintage pieces and books published before 1970. The value must be in English (no or false). If you set no and Google finds evidence that the product does have an identifier, the product gets a warning. Don't use it as a shortcut on branded goods with a missing barcode.

Want the bigger picture of how product data moves through Google? Our explainer on what Google Merchant Center is covers feeds, free listings and the Google Ads link.

How do you fix GTIN errors in Google Merchant Center?

Open Products › Needs attention, filter by the issue name, fix the gtin value at the source, and wait for the next sync. Google says fixes can take 24 to 72 hours to clear from the Needs attention list. Each issue below has its own cause, so match the name first.

Limited performance issues don't stop a product from showing, but Google says such products may get limited visibility. Incorrect and invalid values are more serious, because the product data specification ties incorrect GTINs to disapproval.

To fix many products at once, use the download icon on the Needs attention tab to export a CSV of every affected item. Correct the values where the data comes from, which is your store or your feed file. If you edit a product in Merchant Center while Shopify or WooCommerce syncs it, the next sync can bring the old value back.

Shopify warns that incorrect identifiers can stop products from publishing and can put the account at risk of suspension. If GTIN problems sit alongside a suspension notice, our Merchant Center suspension recovery team can check whether the identifiers are part of the cause.

Where do you add a GTIN in Shopify, WooCommerce or a product feed?

Each platform keeps the GTIN on the variant, because each size and color has its own number. Add it once in your store, and the Google connector sends it to Merchant Center as the gtin attribute.

Shopify

• Open the product, then the variant, and find Barcodes in the Inventory section. Per Shopify's product details guide, each barcode has a type: Custom, GTIN, UPC, EAN, ISBN or ASIN. Choose the type that matches the number instead of leaving it on Custom.
• Shopify's Google & YouTube channel requirements say a product that has a GTIN needs it before it can publish. For products without one, add MPN and brand in the Google & YouTube channel.
• Don't type the SKU into the barcode field to make a warning go away. That trades a limited performance issue for a disapproval.

WooCommerce

• Since WooCommerce 9.2 (August 2024), the Inventory tab has a field labeled GTIN, UPC, EAN or ISBN, on both products and variations. WooCommerce checks that each value is unique across the store.
• The Google for WooCommerce extension also has a Google for WooCommerce tab in Product data where you set GTIN, MPN and brand per product, plus an attribute mapping tool for whole categories.
• For custom or handmade products, WooCommerce's Google for WooCommerce error guide suggests leaving GTIN blank and using the SKU as MPN.

A product feed file

In a CSV or TSV feed, add columns named gtin, brand, mpn and, where needed, identifier_exists. In XML, use <g:gtin>3234567890126</g:gtin> and <g:identifier_exists>no</g:identifier_exists>. Google accepts up to 10 GTIN values per product, which helps when a product carries both a UPC and an ISBN.

If you send products through an API, note that Google sunset the Content API for Shopping on August 18, 2026. Integrations now use the Merchant API, where identifier_exists takes true or false. Our step-by-step guide to Google Merchant Center setup covers connecting each platform for the first time.

How do GTINs help Shopping ads reach the right searches?

Shopping ads have no keywords. Google decides which searches your product can show for by reading your product data, and the GTIN is the most exact part of it. Google says unique product identifiers help match search queries with your products, and that accurate matching can't be assured when the GTIN is missing.

A correct GTIN does three things for your ads and free listings:

• Makes the listing easier to find. Google says a GTIN helps make your ad or free listing easier to find, because it tells Google exactly which product you sell.
• Links your offer to the same product at other stores. The same product carries the same GTIN at every retailer, which is how Google knows your offer and a competitor's are one item.
• Opens price benchmarks. Merchant Center's Analytics › Pricing tab only shows benchmark prices for products with a valid GTIN, since benchmarks come from every retailer selling the same GTIN.

Google has put a number on it before. In a January 2017 post on the Google Ads blog, it said merchants who added correct GTINs saw conversion rates increase up to 20%. That figure is old, but the direction still matches Google's current help pages, which say products with an assigned GTIN submitted without one may have limited visibility.

GTINs feed Performance Max product ads the same way, because those campaigns read the same Merchant Center data. For how product data turns into bids and placements, see our guides to Google Shopping ads and Performance Max campaigns.

What does a clean GTIN setup look like for a small store?

A clean setup gives each product the identifier it really has and nothing it doesn't. Here is an illustrative example, not a client result: a US home goods store with 60 products in three groups.

For the 18 own-label candles, the GS1 US price list sets the trade-off. Eighteen single GTINs cost 18 × $30 = $540 once, with no renewal. A 10-GTIN prefix is too small. A 100-GTIN prefix costs $750 up front and $150 a year, but leaves 82 numbers for new scents. If the line will stay small, single GTINs cost less. If the store plans to add a few dozen products, the prefix pays for itself sooner.

Check the boxA barcode on the packaging? Copy that GTIN

Ask the makerNo barcode? Ask the manufacturer or supplier

Own brand?License GTINs from GS1, or send brand plus MPN

Custom or vintage?Blank gtin and identifier_exists set to no

Before you upload, run this check on the whole catalog:

• No SKU, order number or made-up value sits in the gtin field
• Every size and color has its own GTIN, with variants grouped by item_group_id
• No GTIN starts with 2, 02, 04, 05, 98 or 99
• Products without a GTIN carry brand plus MPN, or identifier_exists set to no
• The brand matches the name printed on the product

If your catalog is large, or the Needs attention tab is full of identifier issues you can't trace, our Merchant Center management service cleans up product data at the source so fixes survive the next sync.