How to Fix Missing GTIN Errors in Google Merchant Center

GTIN warnings are among the most common issues in Google Merchant Center, and among the most misunderstood. Some sellers panic and invent numbers. Others ignore the warning and wonder why their listings get so few impressions. Neither works.

This guide explains what each GTIN message means, when a GTIN is actually required, how to tell Google that a product has none, where legitimate GTINs come from, and exactly where to enter them in Shopify and WooCommerce.

What the GTIN messages mean

A GTIN (Global Trade Item Number) is the number behind a product barcode. It includes UPC (12 digits, common in the US and Canada), EAN (13 digits, used in most other countries), JAN (Japan), ISBN (books) and ITF-14 (cases and multipacks). Google uses it to recognize exactly which product you sell.

In Merchant Center, go to Products > Needs attention to see the issue. You will usually see one of these:

Most "missing" issues are warnings, not disapprovals. The product can still show, but Google's help center says products submitted without the GTIN they have may have limited visibility. On a competitive product, that can mean almost no impressions.

When a GTIN is required and when it is not

The rule is simple: if the manufacturer assigned a GTIN, submit it. If nobody did, do not make one up. Google's product data specification treats GTIN as required for products that have one, and as not applicable for products that do not.

You should submit a GTIN for

• Branded products made by another company and sold by multiple retailers (electronics, toys, cosmetics, books, branded apparel).
• Products you resell or dropship where the manufacturer's barcode is on the packaging.
• Your own brand if you registered GTINs with GS1 and printed them on the packaging.
• Books, which need the ISBN.

You usually do not need a GTIN for

• Private-label products you commissioned without registering barcodes.
• Handmade, custom-made or made-to-order items.
• Vintage items, antiques and one-of-a-kind pieces.
• Many replacement parts, which use brand plus MPN instead.

Bundles and multipacks

For a bundle you put together (for example, a camera with a bag and memory card), submit the GTIN of the main product and set is_bundle to true. For a multipack you create yourself (six of the same item), submit the GTIN of the single item and set multipack to 6. If the manufacturer sells the multipack with its own barcode, use that barcode instead.

How identifier_exists works

The identifier_exists attribute tells Google whether a product has identifiers. It is optional. If you leave it out, Google assumes identifiers may exist and looks at what you submitted.

• If the product has no GTIN, MPN or brand at all, you can submit identifier_exists as no, or simply omit the GTIN, MPN and brand attributes.
• If the product has a brand but no GTIN, submit the brand (and MPN if one exists) and leave GTIN empty. Your own store brand is a valid brand for private-label goods.
• Never set identifier_exists to no on a product that has a manufacturer GTIN. Google checks against its catalog and flags it.

On Shopify with the Google & YouTube app, the equivalent is the Google custom product metafield, set to true for goods with no identifiers.

Where legitimate GTINs come from

Products made by someone else

The GTIN is on the packaging, usually under the barcode. If you do not have the physical product, ask the supplier or distributor for a product data sheet. Brand owners and wholesalers almost always have a spreadsheet with GTINs for every variant. For dropshipped goods from marketplaces, be realistic: many generic products have no real GTIN. In that case, treat them as no-GTIN products and submit an accurate brand only if there truly is one.

Your own brand

GTINs are issued by GS1, the nonprofit that manages barcode standards, through its member organization in your country (GS1 US in the United States). You can license a company prefix, which lets you create many GTINs, or in some countries buy individual GTINs for a small catalog. Once registered, each variant (every size and color) needs its own GTIN.

Checking a GTIN before you submit it

A valid GTIN has 8, 12, 13 or 14 digits, contains only numbers, and ends with a correct check digit. Use our GTIN lookup tool to validate a code and see its format before you paste it into your store. The check digit catches most typing errors. Here is how it works for a 12-digit UPC such as 03600029145X:

1. Add the digits in odd positions (1st, 3rd, 5th and so on): 0 + 6 + 0 + 2 + 1 + 5 = 14.
2. Multiply that sum by 3: 14 x 3 = 42.
3. Add the digits in even positions: 3 + 0 + 0 + 9 + 4 = 16.
4. Add the two results: 42 + 16 = 58.
5. The check digit is what brings the total to the next multiple of 10: 60 minus 58 = 2. The full UPC is 036000291452.

Also avoid numbers starting with prefixes that GS1 reserves for in-store use (such as 2, 02 or 04) or for coupons. Google rejects those in Merchant Center.

Special cases that cause most GTIN confusion

Variants

Each variant is a separate item in Merchant Center, and each one needs its own GTIN. A blue medium shirt and a blue large shirt have different barcodes. Copying one GTIN onto every variant creates duplicate identifiers and mismatch errors, because Google sees several different offers claiming to be the same product.

UPC or EAN when you sell in several countries

You do not need a different GTIN for each country. A 12-digit UPC is a valid GTIN everywhere, and Google also accepts it written as a 13-digit EAN with a leading zero. Submit the number that is on the product, and use the same one in every country's feed.

Used and refurbished products

A used or refurbished item keeps the GTIN of the original product. Submit it along with condition set to used or refurbished. The GTIN identifies what the product is, while condition tells shoppers its state.

Books

Submit the ISBN as the GTIN. If you only have an older 10-digit ISBN, convert it to the 13-digit version (usually starting with 978), since that is the form Google expects.

Dropshipped and imported products

When you import products from suppliers or other stores, check where the barcode came from. Some suppliers fill the barcode field with their own internal codes or random numbers. Those are worse than an empty field. If you cannot confirm that a code is the manufacturer's GTIN, clear it and treat the product as having no GTIN.

Adding GTINs in Shopify

Shopify has no field called GTIN. The Google & YouTube app reads the Barcode field on each variant and sends it as gtin.

1. Go to Products and open the product.
2. For a product without variants, scroll to the Inventory section. For a product with variants, click a variant to open its page.
3. Enter the digits in the Barcode (ISBN, UPC, GTIN, etc.) field. No spaces or dashes.
4. Make sure the Vendor field holds the real brand, since the app sends it as brand.
5. Save. The app syncs the change, usually within hours.

For more than a handful of products, use the bulk editor (select products, choose Bulk edit, and add the Barcode column) or export a CSV and fill the Variant Barcode column. Our Shopify bulk edit guide walks through both.

A note on barcode labels: our Shopify barcode generator creates printable, scannable barcode images from codes you already have, which is useful for labeling stock and scanning at a warehouse or point of sale. Generating a barcode image does not register a GTIN with GS1. For Google, only real registered GTINs count.

Adding GTINs in WooCommerce

Since WooCommerce 9.2 (released in August 2024), WooCommerce has a built-in field for identifiers.

1. Go to Products and edit the product.
2. In the Product data box, open the Inventory tab.
3. Enter the number in the GTIN, UPC, EAN, or ISBN field.
4. For variable products, open the Variations tab, expand each variation and fill its own GTIN field.
5. Update the product.

How the number reaches Google depends on your feed plugin. Google for WooCommerce and most feed plugins can map this core field to gtin, but older setups may still read a plugin-specific field. Check the plugin's attribute mapping settings and confirm in Merchant Center that the GTIN arrived. If you need to update many products at once, see how to bulk edit WooCommerce products.

Fixing GTIN issues across a whole catalog

For a store with hundreds of affected products, work in batches:

1. In Merchant Center, open Products > Needs attention, click the GTIN issue and download the list of affected products.
2. Split the list into three groups: products with a real GTIN you can find, products that genuinely have none, and products with a wrong GTIN.
3. For the first group, collect GTINs from packaging or supplier data sheets and validate each one.
4. For the second group, set brand and MPN where they exist and mark the rest as custom products (or identifier_exists set to no in a feed).
5. For the third group, remove the wrong value first, then add the correct one if it exists.
6. Update the store in bulk and let the feed resync. Check Needs attention again after two or three days.

Expect the warnings to clear gradually rather than all at once. The store update reaches Merchant Center when your feed or app next syncs, and Google then reprocesses each item. For app-based feeds that is usually within a day, while scheduled file feeds depend on the fetch schedule you set. If a warning persists after a week on a product you are sure has the right GTIN, check that the brand matches the GS1 registration and that the value in Merchant Center (open the product and view its attributes) matches what you entered.

The AM Jarvis GMC Scanner and Fixer flags products with missing GTIN or brand in a connected Shopify or WooCommerce store, alongside other Merchant Center problems, and pushes fixes back in batches. It will not invent GTINs for you, which is the point: the numbers still need to come from the manufacturer or GS1. For how the fields flow from Shopify to Google, see setting up a Google Shopping feed on Shopify.