Barcode Format

We normally supply EAN-13 format barcodes. These are the most common retail barcodes in New Zealand and are, in fact, more common in all countries except for the USA and also Canada. We supply these 13-digit numbers with a leading ‘0’, which essentially makes the barcode an EAN-13 format barcode. If a UPC-A barcode is required (for example, for supplying stores in the USA), the EAN-13 format can also be used as a UPC format barcode.

As shown below, the actual bars of an EAN-13 with a leading ‘0’ and a UPC barcode without the leading ‘0’ are identical. The only difference is in the distribution of the numbers below. This means that scanners read both versions in the same way. If a store needs a UPC-A barcode, they can ignore the leading ‘0’ in an EAN-13 barcode.

Why does this occur?

Each digit is encoded into a barcode as 7 blocks of either white or black. A full set of digits 0-9 is called a parity. Retail barcodes have a minimum of two 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 two different parities: a left-side odd parity and a right-side even parity (each with 6 digits).

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. Hence, it employed both the left odd parity and the right even parity of the UPC barcodes, but added parity (a left-even parity) 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 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 start can sometimes be confused by scanners as a UPC barcode without the ‘0’. This largely depends on what the scanner or software system is expecting to see. Often, this occurs when a barcode is first scanned. The software has no point of reference for what format the barcode should be. Hence, it assumes that it is UPC format. When the first number, the 0, is typed in, the system remembers the leading 0.

Generally, when stores add the barcodes based on the information provided on their buyer form or buyers portal, it tends to scan as an EAN-13 format barcode.

Very few stores have had issues with this in the past. And when issues occur, they are generally resolved easily by manually entering the lead 0 on the first scan. Normally the scanner system will then remember that lead 0 when subsequent scans are made.

More information about barcode format

For more information, please see these guides: Choosing the Right Barcode for Retail Products in New Zealand and The Differences Between EAN-13 and UPC Barcodes

Please contact us if you have any questions about this.