ISBN (International Standard Book Number)

An ISBN (International Standard Book Number) is a unique 13-digit numeric identifier assigned to each edition and variation of a book. Audiobooks require their own ISBN, separate from the print or ebook edition, because they constitute a distinct format of the same work.

ISBNs are administered by national agencies. In the United States, Bowker is the exclusive ISBN agency. ISBNs can be purchased individually (around $125 each) or in bulk (a block of 10 for $295, or 100 for $575). Some self-publishing platforms like Amazon KDP provide free ISBNs, though these are tied to that platform and cannot be used elsewhere.

For audiobook distribution, having your own ISBN gives you more control over your metadata and distribution options. Without an ISBN, you are typically limited to the platform that assigned the identifier. With your own ISBN, you can distribute through multiple channels and maintain consistent cataloging across retailers.

When creating AI audiobooks for commercial distribution, authors should factor in ISBN costs as part of their publishing budget. Each format (hardcover, paperback, ebook, audiobook) needs its own ISBN. If you release the audiobook in both abridged and unabridged versions, each version requires a separate ISBN.