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Amazon Mastery: Decoding ASINs, GTINs, EANs, UPCs

23/08/2021 & 16:58 PM


Uploaded By: Admin

Amazon Mastery

Getting to know the acronyms – the catalogue listing

Amazon sells all of the items on its site from a catalogue. If your items are already in that catalogue you can sell them by simply referring to the specific item - you don’t need to upload a description or title as it is already there.

When an item is added to the Amazon Catalogue for the first time it is given a GCID – a Global Catalogue ID – so every item gets a number associated with it. In addition to that GCID, when a retailer adds an item to the Amazon Catalogue they may choose to provide a Standard Product ID – a barcode. Normally adding a barcode is essential, though in some cases where the product added is manufactured by the company listing it, they may instead choose to simply refer to the part number of the item and avoid the need to create a barcode. The Amazon recommendation is to make use of a barcode. If you are adding your own manufactured or licensed products you can find out more on the Amazon Brand Registry pages within your Seller Central account.

Barcodes are everywhere in the retail landscape and a number of international standards exist to manage them. Typically you’ll be able to obtain the correct barcode from the supplier or manufacturer of the items you are selling.

The source of the ASIN

As we know Amazon started as an online bookseller, so it seems appropriate to start with mentioning ISBN. The International Standard Book Number (ISBN) appears on the rear of most books and identifies the country, the publisher and the book. The ISBN numbering system has been extended over the years, but always starts with the letters ISBN.

The ISBN leads us to the ASIN, Amazon Standard Identification Number. To begin with, the ASIN was simply the same as the ISBN – remember Amazon started as a bookseller. But when Amazon increased its number of categories it also had to extend the use of the ASIN. Each product within Amazon has an ASIN and if you want to sell items on Amazon you’ll need to find out what the ASIN is.

Originally ASINs were unique but as the number of products and the number of country-specific Amazons increased ASINs began to repeat. So an ASIN in one country may not necessarily refer to the same product as it does in another. Amazon has been steadily addressing this and regularly update sellers on where ASINs have been brought into line. Nonetheless, the lack of unique ASINs can be a frustration, which brings us to the need for Standard Product IDs.

Standard Product IDs – EANs and UPCs

We’ve already mentioned one Standard Product ID – the ISBN. So let’s look at the other barcodes.

The EAN, European Article Number, is widely used across Europe and other parts of the world. Just as with the ISBN it is a highly structured series of digits, the first few indicating the country – for instance, 50 represents the UK. The remaining digits define the manufacturer and product in question.

The UPC, Universal Product Code, is an American standard used, throughout America and North America. Most barcode readers can read both EAN and UPC barcodes.

Global Trade Item Number

It should be becoming clear that although there is a range of terms it is, nonetheless, all reasonably straightforward. Amazon uses a Global Catalogue ID to manage its extensive catalogue, but each product on the site is allocated an ASIN. Because ASINs are not perfect, it’s important to identify the product with a barcode – normally in an EAN format, or ISBN format if a book of course.

Now that you are familiar with the importance of EAN and UPC barcodes you may wonder who controls them and where you can acquire barcodes if needed. EAN and UPC barcodes are both examples of what is called a GTIN – Global Trade Item Number. The standard for GTIN’s is controlled by, an organisation that controls various international standards. However, you have multiple options on where to buy your barcodes and some barcode sellers will provide you with the barcode in UPC and EAN formats, and in a variety of image formats.

Lastly, let’s briefly mention Stock Keeping Units or SKUs. SKUs can take any form and are used by the holder of the stock to assist in tracking and storing the goods. You may elect to use the SKU of the supplier or to add additional information to it, there is no standard. It’s simply your preferred way of identifying your stock.


It’s easy to get overwhelmed by simple jar-gon but by now you should be a lot more comfortable on what all the terms are and where they come from, in short here is what you need to know:
GCID  the Amazon Catalogue Identifier. Allocated when an item is added to the Amazon Catalogue.
ASIN  The Amazon reference for the product. Though not necessarily unique, so you need to have a bar-code.
Standard Product ID  a barcode in EAN or UPC format or another format such as ISBN. You can buy these from a variety of sites.
SKU  your own internal numbering system for managing your stock. Whatever works for you!
Hopefully, you now know your ASINs from your EANs.