EAN-8 is the short version of EAN-13, the same as UPC-E vs. UPC-A. While they looks very similar, some differences exist. UPC-E does not explicitly encode the first digit(NS) while EAN-8 encodes all 8 digits. That also means that EAN-8 is not compatible with UPC-E from encoding and decoding perspective. Moreover, a UPC-E number can be converted back to UPC-A; however there is no defined method for conversions between EAN-13 to EAN-8.
An EAN-8 number contains 7 digits of message plus 1 check digit. The first two or three digits identify the numbering authority; the remaining 4 or 5 digits identify the product. You must apply the EAN-8 number separately from the numbering agency responsible for your country or region.
The EAN-8 check digit is calculated using modulo 10 method. Here outlines the steps to calculate EAN-8 check digit:
From the right to left, start with odd position, assign the odd/even position to each digit.
Sum all digits in odd position and multiply the result by 3.
Sum all digits in even position.
Sum the results of step 3 and step 4.
Divide the result of step 4 by 10. The check digit is the number which adds the remainder to 10.
A web-based free utility to calculate UPC-A check digit is available at http://www.morovia.com/education/utility/upc-ean.asp.
The encoding of an EAN-8 symbol uses all three two character set. An EAN-8 symbol has the following structure:
Start guard bars, always with a pattern bar+space+bar.
Two number system characters, encoded with character set A.
The following two characters, encoded with character set A.
Center guard bars, with a pattern space+bar+space+bar+space.
Last three characters, encoded in character set C.
Stop guard bars, always with a pattern bar+space+bar.