When should EAN-13 be used, and when should UPC-A be used?

UPC-A barcodes are traditionally used in the United States, while EAN-13 barcodes are commonly used in the rest of the world. Today, most stores globally can accept both barcode formats. However, some older systems may still exist that only accept one of them. Therefore:

· If your product is sold in the United States, it is best to use a UPC-A barcode;
· If your product is intended for the international market or sold in countries outside the United States, an EAN-13 barcode is more appropriate.

If your EAN-13 or UPC-A barcode is not recognized by the system in certain stores, the retailer simply needs to choose to ignore the leading “0” or add a leading “0” according to their system requirements. Once processed this way, the barcode will be read exactly like the other format (since the bar pattern itself is the same) and will still maintain global uniqueness.

UPC and EAN-13 codes can be purchased here.

How are EAN-13 and UPC-A barcodes encoded?

Each digit in a barcode is encoded by 7 black or white modules. A complete set of codes representing the digits 0–9 is called parity. Retail barcodes contain at least two types of parity: one set on the left and one set on the right, to ensure the digits are read correctly even when the barcode is scanned upside down.

The original 12-digit UPC system was created by George Laurer in the 1970s. UPC barcodes use two types of parity:
· Left side: left odd parity
· Right side: right even parity
Each side contains 6 digits.

The 13-digit EAN-13 system that appeared later is a superset of UPC. To maintain compatibility with UPC-A, EAN-13 continues to use UPC’s left odd and right even parities, while adding a new left even parity, which is applied to some of the digits on the left side. Both the left and right sides of an EAN-13 barcode still contain 6 digits each.

Therefore, the first digit determines which combination of the newly created left even parity will be used for the first six digits.
In other words, in any EAN-13 barcode, the first digit itself is not directly encoded into the barcode, but it does determine how the subsequent digits are encoded.

For barcodes starting with “0”, this zero determines that all of the first six digits use left odd parity.
This means that these barcode patterns look identical to UPC barcodes without the leading “0”—because the UPC format also only uses left odd parity.

Since what is actually scanned are the black and white bars of the barcode itself (meaning the scanner does not read the numbers below the barcode), an EAN-13 barcode with a leading “0” can sometimes be mistaken by a scanner for a UPC barcode without the “0”, and vice versa.
This situation mainly depends on the barcode format the scanner or software system expects to read. This often happens when first entering a new barcode into a system—because the system has no reference point to determine which format it should belong to, it defaults to treating it as a UPC format.

In the past, very few stores encountered this problem, and when it did occur, it was generally easy to resolve.

We recommend:
When first adding a barcode to a new retail system, do not scan it directly; instead, manually enter the barcode number and then associate it with the product information and price.
Once these steps are completed, when the barcode is scanned through that system again, it will appear in the correct format (EAN-13 or UPC, depending on the format used when it was initially entered into the system).

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