ISBN

An ISBN (International Standard Book Number) is a unique number that identifies one specific edition and format of a book. Retailers, distributors, wholesalers and libraries use it to order, track and catalog titles. ISBNs have had 13 digits since 2007; older books may also show a 10-digit version. In print, the ISBN appears on the copyright page and above the barcode on the back cover.

ISBNs are issued by a national agency in each country, such as Bowker in the United States and Nielsen in the United Kingdom. Some countries, including Canada, issue them free to local publishers. The agency records who the publisher is, so whoever obtains the ISBN is the publisher of record for that edition.

Why it matters for indie authors

Every format needs its own ISBN. The paperback, the hardcover and the ebook are separate products, and so is an audiobook if you assign it one. A substantially revised new edition gets a new number; correcting typos does not.

On Amazon, Kindle ebooks don’t need an ISBN, because Amazon assigns its own ASIN. Paperbacks and hardcovers do. KDP offers a free ISBN for print books, but it lists “Independently published” as the imprint and can only be used for distribution through KDP. If you want the same edition printed through another service, such as IngramSpark, or want your own imprint name on record, use an ISBN you obtain yourself.

Example

An author is publishing a gardening guide as a paperback, a hardcover and an ebook. She buys a block of ISBNs from her national agency, registers them under her imprint name and assigns one to each format, so each edition’s copyright page lists its own number. Because she owns the paperback’s ISBN, she can use it on both KDP and IngramSpark; she leaves KDP’s Expanded Distribution off, since IngramSpark covers bookstores. The ebook gets the third number, which she uses in every store that sells it.

Common mistakes

• One ISBN across formats. The paperback and the hardcover each need their own.
• Expecting an ISBN to protect copyright. It identifies a book; it doesn’t register or protect your rights.
• Starting with KDP’s free ISBN, then going wide in print. That number can’t move to another printer, so the edition elsewhere needs a new one.
• Changing trim size and keeping the number. KDP doesn’t let you change a published paperback’s trim size in place; a new size means a new edition with a new ISBN.
• Reusing a number. Once an ISBN has been assigned to a published book, it stays with that book.