ISSN Barcode Structure for Serials

What is an ISSN?

The International Standard Serial Number (ISSN) identifies continuing resources like newspapers, journals, magazines, and academic serials.

While a base ISSN assigned by the National Centre is exactly 8 digits long, the version printed on physical retail covers must be mathematically formatted as a specialized 13-digit EAN-13 barcode in order to be scannable in bookstores and checkout registers.

The 13-Digit EAN Wrapper

To print an ISSN for retail, the 8-digit identifier must be converted as follows:

1. GS1 Prefix: Every ISSN-based barcode must start with the mandatory 977 prefix, identifying it globally as a periodical.
2. Base ISSN Payload: The first 7 digits of the assigned 8-digit ISSN (the original 8th check digit is discarded).
3. Sequence Variant: Two digits (usually 00) used by publishers to track special issues, price changes, or variants of the same title without needing a new ISSN.
4. Check Digit: The final 13th digit, calculated using the standard EAN-13 Modulo 10 algorithm to validate the entire string.

Add-on Issue Coding (2 or 5 Digits)

Because a magazine retains the same ISSN month after month, publishers need a way to track individual issues. To solve this, publishers append a smaller 2-digit or 5-digit supplemental barcode (Add-on) to the right of the main ISSN symbol.

This Add-on typically represents the month (01-12), week, or the specific issue number, allowing retailers to distinguish between different editions of the same publication and clear out old stock.