The Author's Complete ISBN and Barcode Guide

What Is an ISBN?

An ISBN is the universal identity card for your book. It is a 13-digit number that uniquely identifies a specific edition, format, and publisher of a title. Every major retailer, library, and distribution system relies on the ISBN to track inventory, report sales, and calculate royalties. Without it, your book simply does not exist in the global retail ecosystem.

ISBN vs. ASIN: What's the Difference?

Amazon assigns its own ASIN (Amazon Standard Identification Number) to every product. If you publish exclusively through KDP without providing an ISBN, Amazon gives your book an ASIN — but that number only works within Amazon. Bookstores cannot order your book, libraries cannot catalog it, and major distributors like Ingram will not recognize it. For wide distribution, you need a proper ISBN.

How to Get an ISBN

• United States (Bowker): myidentifiers.com — Single ISBN $125, block of 10 costs $295
• United Kingdom: isbn.nielsenbook.co.uk — Block of 10 costs £164
• Free ISBNs from KDP or IngramSpark list the platform as publisher of record — for professional publishing, buy your own

Understanding the EAN-13 Barcode

The ISBN barcode is an EAN-13 barcode (European Article Number, 13 digits). Digits 1-3 are the country prefix (978 or 979 for books globally), digits 4-12 are the publisher and title identifier, and digit 13 is the mathematically derived check digit.

The Price Extension (EAN-5)

The 5-digit extension barcode to the right of the main ISBN encodes the retail price. The first digit is the currency indicator, and digits 2-5 are the price in cents.

Barcode Placement on Your Cover

• Standard placement: bottom-right corner of the back cover
• Minimum size: 1.5" wide x 1.0" tall
• Background: pure white only (#FFFFFF)
• Quiet zone: at least 0.25" of white space on all four sides
• No text or design elements inside the quiet zone