Do You Need an ISBN to Self-Publish?
You don't strictly need to buy an ISBN. KDP gives paperbacks a free one, and Kindle ebooks need none. But a free KDP ISBN lists Amazon as the publisher of record and can't move with you to other stores. If you want your own imprint on the book and the freedom to distribute anywhere, buy your own. For a single Amazon-only paperback, the free one is fine.
The ISBN question trips up nearly every first-time self-publisher, usually because the answer is “it depends” and nobody says on what. It depends on two things: where you’re selling, and whose name you want listed as the publisher.
What an ISBN actually is
An ISBN is a unique identifier for one edition of one book. The important word is edition. Your paperback and your ebook are different editions, so they need different ISBNs. A hardcover would be a third. It’s not “one number per book,” it’s one per format.
The free KDP ISBN
KDP will hand your paperback a free ISBN, and for a lot of people that’s fine. Two catches worth knowing before you take it:
- It names an Amazon-owned imprint as the publisher of record, not you.
- You can’t reuse it anywhere else. It’s locked to KDP, so you can’t take that same edition to IngramSpark later.
If your plan is one paperback, sold on Amazon, and you don’t care whose imprint shows up in the metadata, the free one does the job.
Buying your own
Your own ISBN puts your imprint on the record and travels with the book to any store or printer. You buy them from your country’s agency: Bowker in the US, Nielsen in the UK, and in some countries (Canada among them) they’re free.
The catch in the US is cost. One Bowker ISBN is pricey per unit, but a pack of ten drops the per-book price a lot, and if you’re publishing more than one book, or one book in paperback plus ebook plus hardcover, you’ll want several anyway. Buy in bulk if you’re buying at all.
Ebooks
Kindle doesn’t require an ISBN. It uses Amazon’s own ASIN, so you can publish a Kindle ebook with no ISBN at all. Some other stores, like Apple Books, prefer or require one. If you’re going wide with your ebook, having your own ISBN keeps things clean across stores.
The short version
Amazon-only paperback, don’t care about the imprint: take the free one. Want your own imprint, or want to sell anywhere: buy your own, in a pack. Either way, Galley stores your ISBNs with the book and drops them onto the copyright page and into the export metadata for you.
If you already have an ISBN in front of you, the ISBN checker tells you whether the check digit adds up and converts between the ten and thirteen digit forms.
More on publishing
- Standard Manuscript Format, and What Agents Actually CheckThe Shunn manuscript format specification in plain terms: font, spacing, margins, indents, scene breaks, the running header, and the word count that should be rounded.
- Writing Software for Novelists Who Don't Write in EnglishHow to write and typeset a book in Arabic, Persian, Urdu, Hebrew, Hindi, Bengali, Thai, Japanese, Chinese, Korean, Russian, Greek or Vietnamese, which typeface each script gets, and what still needs building.
- Accessible Ebooks and the European Accessibility ActWhat the EAA means for a self-published novel sold in the EU: accessibility metadata, what makes an EPUB accessible, the microenterprise exemption, and the large-print edition nobody makes.