What is a GTIN?
The GTIN (Global Trade Item Number) is the global item number of the GS1 organisation. According to GS1 Germany, it can be used to identify every item, product and product variant worldwide without overlap.
In Europe, the number used to be called the EAN (European Article Number). Since 2009, GS1 has officially used the term GTIN (GS1 Germany on the EAN). In retail and in many shop systems, however, “EAN” is still common. In Germany, it almost always means the 13-digit GTIN, which consists of three parts:
- GS1 company prefix of 7 to 9 digits, issued by GS1 Germany,
- individual item reference of 3 to 5 digits, assigned by the company itself,
- check digit of one digit, used to check whether the number is valid.
GTIN formats: EAN, UPC, GTIN-8 and GTIN-14
The GTIN comes in four lengths. Google describes the formats in its help pages on unique product identifiers and on the gtin attribute:
- GTIN-13 (EAN): 13 digits, the standard in Germany and outside North America.
- GTIN-12 (UPC): 12 digits, mainly in North America.
- GTIN-8: 8 digits, intended for small items according to GS1 Germany.
- GTIN-14: 14 digits, listed by Google as ITF-14 for multipacks. According to GS1 Germany, it is formed on the basis of the 13-digit GTIN.
Books have an ISBN. The 13-digit ISBN usually starts with 978 or 979 and is also accepted by Google as a GTIN. Google ignores spaces and hyphens in the number.
Where do you get a GTIN?
If you sell products from other manufacturers, you do not assign your own GTINs. Google advises checking the number on the packaging or asking the manufacturer or distributor (Google Help).
If you manufacture your own products, you get GTINs in Germany from GS1 Germany, the official provider. GS1 Germany offers packages for this, such as SmartStarter10 with ten GTINs for companies with an annual turnover of up to 250,000 euros and GS1 Complete with larger number ranges. Both packages include a Global Location Number (GLN), which identifies the company uniquely worldwide (GS1 Germany). GS1 Germany also points out that many retailers and online marketplaces only accept numbers officially issued by GS1 (GS1 Germany on the EAN).
GTIN in Google Merchant Center
In the product data specification, the GTIN is strongly recommended if the product has one. According to Google, products that have a GTIN but are submitted without it may have limited visibility. Two further identifiers play a role alongside the GTIN:
- brand: the brand is required for all new products, except films, books and music.
- mpn: the manufacturer part number is only required if the product does not have a GTIN assigned by the manufacturer. It may be up to 70 characters long.
For products without a GTIN, MPN or brand, there is the identifier_exists attribute. Google recommends the value “no” for custom goods, handmade items, vintage and antique products and books published before 1970, for example. You should only set it if you are certain that there is no identifier: if it is wrongly set to “no” and there is evidence of an identifier, the product receives a warning (Google Help). We describe how we check and complete product data in Merchant Center on our Google Merchant Center page.
Typical GTIN errors
- Wrong check digit: the last digit does not match the others, for example after typing errors or when spreadsheet programs remove leading zeros.
- Restricted ranges: according to Google’s help page on the gtin attribute, GTINs with the prefixes 02, 04 or 2 (restricted ranges) and 05, 98 or 99 (coupon ranges) must not be submitted.
- Wrong length or characters: Google expects 8, 12, 13 or 14 digits and no letters.
- GTIN of another product: if all variants use the same number or it comes from a similar item, the data is wrong.
- identifier_exists set incorrectly: the value “no” for a product that has a GTIN leads to a warning.
Google describes the consequences in its help page on the gtin attribute: products with a missing or incorrect GTIN may have limited visibility, and accurate matching to the product cannot be assured without a GTIN.
GTIN in the ChatGPT product feed
The product feed for ChatGPT also has a gtin field. In OpenAI’s own format, it is optional according to the feed specification. If it is filled in, it must contain exactly one GTIN of 8, 12, 13 or 14 digits, including a valid check digit, with leading zeros and without spaces or hyphens. If you submit a Google-compatible feed instead, you must provide a valid GTIN or MPN unless identifier_exists is set to “no”. According to OpenAI, the MPN should be submitted together with the brand, and a missing GTIN should not be replaced with an invented value.
Our Rheinwunder Feed Manager, which we use to create the ChatGPT product feed, checks GTINs from the existing feed using the check digit. Our feed optimisation page gives an overview of all channels.
Would you like to complete your product data with correct GTINs and need support? Then get in touch or read more about our Merchant Center optimisation!
