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4: Understanding barcode rules

A barcode visually represents numbers, letters (and other characters) using combinations of light and dark bars so scanners can read them quickly and accurately. Black and white bars create the most effective barcode images, although some other combinations can be used.

In retail, barcodes are printed on product packaging or labels for scanning at the point of sale. When the barcode is scanned the GTIN is decoded, identifying the product and providing access to further product information stored on the retailers’ computer systems, such as the product price.

There are different barcodes types for consumer units, cases or pallets. Here is a quick overview of commonly used ones.

Barcode types


Items scanned at the retail point of sale are usually identified using an 8- or 13-digit GTIN. This is then displayed in a GS1 barcode – also known as an EAN-8 or EAN-13 barcode.

Outer cases

For cases scanned in a warehouse or distribution centre you may use any of the following coding symbols – depending on the type of outer case packaging material or the type of information required by trading partners. These include:


This is for printing on a separate case label OR for direct printing on to high quality casing material.
✓ This barcode will also scan at point of sale.


This is for printing directly on to poor quality case material such as fibreboard and certain types of cardboard.
This barcode will not scan at point of sale.


This enables you to encode additional information such as best before dates or batch numbers, as well as the GTIN. It can also represent other types of GS1 identification numbers, such as SSCCs.
This barcode will not scan at point of sale.

Logistics units and pallets

These are identified with an SSCC usually encoded in a GS1-128 barcode – and then printed in a standard GS1 Logistics Label.

Your trading partners will usually tell what type of barcode and label you need to use on your cases and pallets so make sure you ask them.

How do I create my barcode images?

You can do this either through GS1 UK or by getting in touch with one of our accredited solution providers. 

Go to My Numberbank to find out more.

Barcode image rules

It’s vital that you print barcodes accurately so that they scan as they should at point of sale and point of delivery. If you don’t, you may face problems such as:

  • Costly re-packaging
  • Unnecessary delays at retail stores
  • Lost sales

Each barcode image must meet guidelines that specify:

  • Bar height
  • Barcode position on the label or packaging
  • Barcode colour and background
  • Barcode print quality

Your packaging designer or provider will normally be familiar with these rules and will make sure the barcode is compliant. But if you need more information, you can view our detailed guide ’Barcoding: getting it right’. 

How do I make sure my barcode works?

You can either validate your barcodes to check their format accuracy, or verify them for consistency at the point of production.


Our validation service checks a PDF version of any barcode images you create – using a barcode verifier that meets our latest global standards. This process checks:

  • The GTIN is in the right format showing correct use of the company prefix
  • Colours are used appropriately
  • The barcode is within the right range of sizes and proportions
  • The barcode is positioned correctly on your product


You can also physically send your product in its barcoded packaging to one of our accredited solution providers who will verify it to make sure it is printed correctly.

You can even go one step further and install specialist verification equipment on your production line to check barcode quality and consistency as your products are made. Contact one of our solution providers for more information.