What Is In a GS1-128 Number

April 17, 2013

If your company ships product anywhere, then you may need shipping labels that contain a GS1-128 number and mating bar code. 

For this you need a GS1-128 company prefix number. The company prefix number is assigned exclusively to your company by the GS1 organization. It registers the number and maintains its link to your company on a yearly basis. When trading partners scan your bar coded containers, they know it came from your company. If you’re also sending 856 advance ship notices to them, then they can link that bar coded value to their purchase order and the 856 transaction. In fact, they can determine exactly what’s in the container without opening it!
So what is the GS1-128 number? The number consists of several pieces. Each piece has its own position within a total length of 20 digits.

The first two digits comprise the App ID#, 00, which converts an 18 digit SSCC-18 value into the 20 digit GS1-128 format.

The third digit is the Extension Digit was originally used as a package identifier digit, where 0 indicates a carton label number and 1 indicates a pallet label number. Today, it’s a user defined digit. It can function as an extension to the sequential counter part of the number, increasing its value by one extra digit, or can have any meaning as determined by the company using it.

The fourth digit identifies the country for the GS1-128 number. 0 represents North American companies. The GS1 organization assigns this value.

The GS1 Company ID# is the next section and its length can vary from 6 to 10 digits with leading zeros when needed. The number of digits is determined by the GS1 organization and is based on how many product numbers you ship. If you have just a few product numbers, then the Company ID# could be a 10 digit value. This results in having only 5 digits for the sequential counter value before rolling over to restart at 00000. If you have many product numbers, then the Company ID# would be at minimum, a 6 digit value. This allows for having a sequential counter value up to 9 digits long. The GS1-128 number must not be repeated within one year on your shipping labels.

The final digit in the GS1-128 number is referred to as a check digit. Its value is calculated from the previous 19 digits, and uses an algorithm known as Modula 10. Details for this method can be found on the GS1US.org website.

So the next time someone mentions GS1-128 bar codes, you’ll have a better understanding of what they are. Contact 1EDISource for solutions concerning GS1-128 bar codes and all EDI issues.