This first component, the UPC Company Prefix, is between 6 and 10 digits and is assigned to you by GS1. Also, the number of digits is determined by how many products you will need to assign numbers to. But, if you have thousands of products, your company prefix will need to be fewer digits. If you have just a few products, your company prefix will likely be closer to 10 digits long. This company prefix number will define you as the manufacturer of all of your products, as well as in any EDI (Electronic Data Interchange) applications.
The next component is a unique number used to reference a specific product. It is called an “Item Reference Number.” This number is not assigned by GS1, it is up to the manufacturer to assign the unique Item Reference Number for a given product.
The last component is a number check digit calculated from the previous 11 digits. It is not randomly assigned. The barcode label printing software you use will calculate this check digit for you.