GS1, an international standards organization, maintains the requirements for barcode labeling of retail items. There are several commonly used formats for product identification depending on the item, country, and space available on label.  UPC and EAN are the two most common examples.

The GS1 specification is very detailed and technical. It requires the manufacturer to register the product and company code to get a valid UPC / EAN number.   That number then needs to be encoded into a UPC barcode that meets the stringent GS1 requirements.  Most industrial labeling software applications help the user to design labels with UPC / EAN compliant barcode without requiring them to know the specification.

Why Create GS1 Compliant UPC / EAN Product Labels?

The GS1 UPC / EAN specification is the international standard. Most worldwide retail establishments require their vendors to label their product with the UPC / EAN standard barcode.  It allows them to develop and run automated scanning systems to quickly and accurately identify products at the register stand for efficient checkout. Most retailers will REQUIRE their vendors to label their products with this specific barcode that has the valid GS1 approved number encoded in it as a condition of doing business. In other words, there is no choice in the matter.

UPC / EAN barcode is actually a combination of symbology (i.e. type of barcode pattern), data structure (i.e. 12-13 digit code issued by GS1), and layout specification (i.e. detailed description of the size, placement of human readable numbers, height of the barcode lines, etc.).  All of these elements must be done correctly to have a compliant UPC / EAN code.   Modern day barcode scanners are forgiving of barcodes that are not completely in spec.  Therefore it is possible to create a non-complaint UPC / EAN code that will still work at retail.  However, not following the GS1 standard creates the risk of a problem.  Most likely the retailer will require the manufacturer to recall and relabel all products if it is found that the UPC / EAN code is not compliant.

Creating GS1 Complaint Barcodes

The good news is that most industrial label printing software will help the user create compliant UPC / EAN barcodes.  Many of the GS1 rules and requirements are embedded in the software design.  Therefore most of these applications will guide the user to stay in compliance.  Here is what most of the applications do for you:


Barcodes come in different 'languages' or symbologies.  Each symbology is a specific pattern of lines and spaces of varying sizes that, when read by a barcode scanner, should quickly, accurately, and consistently produce a string of character.  Since UPC / EAN codes are some of the most commonly used barcodes, just about every labeling software application can accurately create it.  This includes making sure that the lines and spaces are of the correct widths.  The precision is critical.  We have seen cases where someone, for example, takes an image of a valid barcode and makes it 'invalid' by stretching it to a different size.  Using the barcode feature in professional labeling software will make sure the lines rendered are within GS1 specifications.

Data Structure

The data structure of the standard GS1 UPC / EAN code is:

  • Company code (5-6 digits)
  • Item code (6 digits)
  • Check digit

GS1 must be contacted so your company and item can be registered and assigned a valid number:

The labeling software cannot issue a GS1 number.  However, it can help to make sure that you are using the number correctly.  For example, most industrial labeling software will not allow the user to enter an invalid number of digits, enter any non-valid characters (UPC / EAN are all numeric) and often will calculate the last 'check digit' for you.

The example to the right shows a commonly used application, CODESOFT, in two situations:

  1. Valid UPC barcode length
  2. Invalid UPC barcode length

Note the software rendering of the barcode no longer shows a barcode.  Also, you can see a "The encoding data does not contain enough characters" warning message.  Both of these are strong indicators to the user that the data and/or structure of the data is invalid.

Layout Specification

GS1 also determines the exact layout of the barcode.  This includes details such as:

  • Exact bar and space width's allowed for the barcode (expressed in 'mils')
  • Barcode height (changes based on placement)
  • Human readable number font size and placement
  • Size of 'quiet zone' needed around the barcode (white space) and around the human readable numbers

Professional grade software will use these requirements to automatically lay out the barcode for the user in the correct format. It will also maintain these specifications if the label or label data is altered or changed.

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