ISBNs
The international ID number for your book. Required in some places, optional in others, free in some places, $125+ in others. Here’s the short version.
When you don’t need one
Amazon Kindle ebooks don’t require an ISBN. Amazon assigns its own internal ID (the ASIN) and that’s enough. If your book is Kindle-only, you can skip ISBNs entirely.
When you do
- Print books always need one. Bookstores and libraries order by ISBN.
- Most non-Amazon ebook stores need one. Apple Books, Kobo, Barnes & Noble, the libraries.
Three ways to get one
- Free from your aggregator
- Draft2Digital and most other aggregators give you a free ISBN if you don’t bring your own. The ISBN agency records the aggregator as “vendor of record” but they don’t take any rights to your book and the publisher you list (your name or your imprint) shows publicly. The catch: the free ISBN is locked to that aggregator. If you later switch, you can’t carry it with you.
- Free from KDP (US writers only)
- Amazon will give you a free ISBN for the print version of your book. Same caveat — it’s locked to KDP and they’re listed as the publisher of record.
- Buy your own from Bowker (or your country’s ISBN agency)
- In the US: Bowker. About $125 for one or $295 for ten. Most countries have their own agency that’s often cheaper or even free. Owned ISBNs travel with the book forever, regardless of where you sell it. If you plan to build a long-term self-publishing business, owning your ISBNs is worth the cost. If you’re trying out one book to see how it goes, free is fine.
One ISBN per format
Every distinct edition needs its own ISBN: the ebook gets one, the paperback gets another, a hardcover gets a third. Same book, three numbers. This is normal and expected by every retailer.