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Barcode Format

Barcodes can come in either EAN-13 format or UPC-A format. Our EAN-13 numbers come in the following format 0123456789104. This can easily be converted into a UPC-A format barcode by removing the leading ‘0’ as follows 123456789104. In both cases, the actual bars of the barcode remain the same. This means that they are scanned in the same way. Some retail systems may only take 12 numbers or only take 13 numbers. In these cases, the retailer can be instructed to either ignore the leading ‘0’ or add a leading ‘0’. The barcode number will still be globally unique worldwide. However, it will adhere to the particular retailer’s requirements. The barcode will still scan in the same way.

See below for a comparison of UPC-A Barcodes and EAN-13 barcodes.


Why this occurs?

The way a digit is encoded into every barcode is seven blocks of either white or black making up each digit. – A full set of digits 0-9 is called a parity. – Retail barcodes have a minimum of 2 parities, one for the left side and one for the right. – This is so they can be scanned upside down and still return the correct number the right way around.

Originally the 12-digit UPC system was created in the 1970s by George Laurer. – these work with 2 different parities – a left side odd parity and a right side even parity (each with 6 digits) – the parities for these can be seen in the attached.

Later, a 13-digit EAN-13 system was introduced as a superset of the UPC barcodes. These were deliberately designed to be used in conjunction with UPC-A barcodes. And hence, employed both the left odd parity and the right even parity of the UPC barcodes but added parity (a left-even parity) which was to be used on a selection of the left-hand side digits –

The left and right-hand sides of the EAN-13 barcodes are still divided into 6 digits each. So the initial digit determines which combination of the first 6 digits will use the newly created left even parity. Hence, in no EAN-13, the barcode is the first digit encoded in the barcode. However, it does determine the way the other digits are encoded.

– In the case of a leading ‘0’ as with our barcodes, the 0 determines that all of the initial 6 digits will use the left odd parity, meaning that the bars look the same as a UPC barcode would without the leading ‘0’ – As the UPC version also only uses the odd parity.

How do they scan?

Because the actual bars are the only part of the barcode that is scanned (i.e. the scanner isn’t reading the digits below the barcode), an EAN-13 barcode with a ‘0’ on the front can sometimes be confused by scanners as a UPC barcode without the ‘0’ and vice-versa. This is largely to do with what the scanner or software system is expecting to see. Often, this occurs when a barcode that is not linked to the system is scanned – The software has no point of reference for what format the barcode should be and, hence, assumes that it is UPC format. When the number is first added to the system in the 13-digit format and linked to the system in the system (generally, how stores add the barcodes based on the information provided on their buyer form), it tends to scan appropriately in EAN-13 format.

Very few stores have had issues with this in the past. And when issues occur, they are generally resolved easily. If you are going to the Musgraves in Ireland, they prefer that you fill out your barcode in its UPC format on their buyer form (without the leading ‘0’) and state that the format is UPC – if this is done, they have no problems using our barcodes.

Please contact us if you have any questions about this.