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GS1 UK and Amazon team up to answer your barcode questions

Date: August 20, 2020

A few weeks ago, we ran a joint webinar with Amazon where we discussed all things barcode related. It was great session with loads of questions from Amazon sellers, including:

  • What is the difference between a UPC, EAN and GTIN?
  • When should I assign a new barcode number?
  • What are the benefits of using barcode numbers on Amazon?

For those of you who weren’t able to make the live webinar, we've provided the answers to the most commonly asked questions below.

If you still have any questions surrounding your Amazon account or how to allocate barcode numbers to your products, please get in touch with our lovely member support team by emailing, or calling us on 020 7092 3501.

So, here goes…

When I go to create a new product listing, I am asked to provide a UPC, EAN and GTIN. What do these codes mean and do I need to provide all three?

Universal Product Codes (UPCs) and European Article Numbers (EANs) are the digits that sit underneath the black and white lines you would recognise as a barcode. However, it is the digits, not the lines, that are used by retailers – both online and in store – to uniquely identify your products. 

Both UPCs and EANs are types of Global Trade Item Numbers (otherwise known as GTINs), but of different lengths: a UPC is typically 12 digits, where an EAN can be either 8, 13 or 14 digits long. 

You only need one GTIN to identify your product, and this code can be used anywhere in the world and by any retailer or marketplace. 

For new starters on Amazon with only a couple of products, what are the benefits using GS1 GTINs when I can get them cheaper from a third party?

Many online sellers do not start by getting their barcode numbers (GTINs) from GS1, they go to third-party providers. However, if you purchase a GTIN from a third-party provider, the GTIN will still belong to that company and is not licenced to you or your brand. 

Down the line, this will cause you issues when listing your products on Amazon, because you run the risk of your products being delisted if the number you are using is registered to somebody else. 

We have seen many cases where sellers did not know that they were using pre-registered GTINs, and have had to go through the headache of reallocating new numbers and updating their packaging across their entire product range – see example here from Sandows. This can lead to a loss of sales data and reviews connected to your products, as well as a significant monetary hit.  

Do I need to allocate a different GTIN (UPC/EAN) for each country I sell in?

No, you only need one identifier for each product. GTINs are a globally recognised standard and will work on any marketplace and in any country. 

Do I need separate barcodes for different sizes or colours of the same product?

Yes, you need to allocate a unique number for every style, colour and size. This is so each of your products can be uniquely identified by search engines, warehouse management tools and point of sale devices, ensuring your customer received the correct item.  

For example, if I sell a white t-shirt in three sizes (small, medium and large), I will need three GTINs for each of the three sizes. If I decided I want to diversify, and sell my t-shirts in a range of other colours, such as red, green and blue, in all three size, I would need a total of 12 GTINs – one for each variation. 

When should I change the GTIN on a current product?

GTINs are used to identify products – anything you can price, order and sell. And a new product will always require a new GTIN. But you will also often have to allocate a new GTIN when you have made changes to a product, for example, if the ingredients have changed significantly, or its size or colour.

Three guiding principles should be considered by any brand owner when introducing changes to an existing product:

  1. Is a consumer and/or trading partner expected to distinguish the changed product from previous/current product – you should consider this particularly when selling online, since a customer might not receive what they think they are purchasing if an incorrect GTIN has been allocated
  2. Is there a regulatory/liability disclosure requirement to a consumer and/or trading partner?
  3. Is there a substantial impact to the supply chain (i.e. how the product is shipped, stored, received)? 

Find out more about GTIN management here.

How do I list products that are "already on Amazon", but are slightly different – such as those that include branded packaging and labelling – so I can apply offers to my own items but not other listings?

If the products in question are branded by your company, you will need to register your brand using the Brand Registry tool in Amazon Seller Central (search for this in the help bar in Seller Central). Once you have registered your own brand, you will be able to then create new product listings under that brand with your own GTINs/barcodes. 

I have a product with an old UPC/EAN code that was purchased from a third-party. This product has around 4,000 Amazon review ratings. How can I switch my old UPC/EAN code to a GS1 GTIN without losing all of those ratings?

This can only be done with the help of Amazon, as they will need to change over the allocated product identifier. Your best bet is to contact help at Seller Central and explain the situation. 

However, if they are not able to help without suggesting you delete your old product listing and create a new product listing with a GS1 barcode, please get in touch with 

Can I reuse a barcode number if the original item is no longer available?

As of 1 January 2019, you can no longer reuse GTINs. This is because e-commerce has changed the way products exist. Even if a product is no longer in production in the physical world, in the digital world it may still be searchable and could cause a clash if the GTIN has been reallocated to a new product. 

You can find out more about the end of GTIN reuse here

If I purchase a product from a supplier who hasn't already applied a barcode, can I allocate a barcode number using my GS1 account or do I need to ask the supplier to do this?

GS1 numbers should be used to uniquely identify products at source, so you will need to ask your supplier to do this. Relabelling later can cause errors and confusion for customers.

Will using GS1 barcodes help to prevent hijackers on listings?

Yes, if you enter your GS1 GTIN in the brand registry and log the number in the GTIN field. This will help you to manage your distribution channels.

Our shop sells across Amazon Handmade. Do we need to allocate barcodes to our products?

You are not required to allocate GTINs to products sold on Amazon Handmade.

I have already used my allocation of 1,000 barcode numbers. How can I get more numbers?

Please contact GS1 UK if you need additional numbers, and we will issue you with an additional company prefix. 

You can contact us on Monday–Friday from 9:00am–5:00pm, by calling 020 7092 3500 or emailing

If I sell my business, can I transfer my GS1 account to the purchaser?

Yes, you can transfer your numbers, but you will need to contact GS1 to update the database to ensure the new ownership is reflected correctly. Otherwise, there will be a discrepancy, which can cause listing issues in the future.

Is there a registration fee for signing up to GS1 UK?

GS1 UK is a membership organisation and your membership is calculated based on your annual turnover and the number of GTINs your require i.e. the number of unique products in your catalogue/range.

You can find out more about GS1 UK membership here.

I just bought some barcodes, why are they not being accepted by Amazon?

There are a number of reasons, why your GTINS/ barcodes have not been accepted by Amazon. Troubleshoot through the error list below to resolve the problem:

  • Invalid error: usually due to not selecting EAN as the product ID type


A very common problem, and it's likely that you have selected the incorrect product ID for your listing. Below is how you can rectify the problem:

When you upload your product into Amazon Seller Central, the first attribute you are asked for is the product ID. This the unique GTIN provided to you by GS1 UK (if you are selling someone else's products then you will need to ask them for the numbers).

Amazon allows you to add:

  • UPC - Amazon is expecting a 12 digit number. It is very unlikely that you would need to select UPC as the 12 digit numbers are for use in certain retailers in the USA only
  • EAN - Amazon is expecting a 13 digit number. Therefore, if you are selling a single product, sometimes called a SKU or a child product if you have variants, you will need to select this option
  • GTIN - Amazon is expecting a 14 digit number. If you are selling a case or box of products - for example a carton of 6 products (that would usually be sold separately) all together, then you need to select GTIN and input the GTIN14 that you have assigned to it
  • A GCID is a number that Amazon gives your product after you’ve registered your brand to use if you have had a GTIN exemption

Please Note: After April 17, 2018, GCIDs can no longer be used in place of a UPC, EAN, JAN or ISBN to create ASINs. If your brand has been approved for the new Brand Registry programme and you do not have UPCs, EANs, JANs or ISBNs for your products, please apply for GTIN Exemption.

For more info, follow the instructions in the video below:

  • Doesn’t match: Usually an issue with the details of the brand name being different to the company details registered with Amazon and/or GS1

Brand issue Amazon

You need to provide Amazon with proof of the connection between the seller and the brand. Things like trademark certificate, invoices to show you bought the stock from the brand or a letter of authorisation to show you are allowed to sell that brand.

  • Potential match:The product you have listed may already be in the Amazon catalogue. You need to check to see if it exists already.