How to self-publish on Amazon KDP · 5 min read
ISBN, explained — what it is, what it costs, and why you want your own
Bowker, KDP-issued ISBNs, free Canadian ISBNs, ISBNs across formats. The 10-minute version of a topic that confuses every first-time author.
An ISBN is the 13-digit identifier on the back of every published book. It does three things: it identifies a specific edition, it lets retailers track the title in their inventory systems, and it appears in metadata that signals to readers and reviewers whether the book is published professionally.
What an ISBN is not
An ISBN is not a copyright. Copyright registration is a separate thing, $65 with the US Copyright Office. An ISBN is just an identifier.
An ISBN is not required for ebook-only KDP publishing. KDP issues an ASIN (Amazon’s own identifier) automatically. You can publish a Kindle ebook with no ISBN.
An ISBN is required for print, on KDP and on IngramSpark. You either bring your own or take a free one.
The four ways to get an ISBN
Bowker (US) — $125 for a single ISBN, $295 for ten, $575 for 100. You buy from myidentifiers.com. Each ISBN is yours forever and identifies you as the publisher. The smartest move for serious authors.
KDP-issued — free, but the ISBN identifies “Independently Published” as the publisher in metadata. Bookstores and libraries de-prioritize KDP-ISBN books. Reviewers sometimes notice.
IngramSpark-issued — also free, identifies IngramSpark as the assigning agency. Slightly better metadata signal than KDP-issued; still not yours.
Free Canadian ISBN — if you are a Canadian citizen, ISBNs are free from Library and Archives Canada. Same usage rules. Smart benefit if you’re eligible.
Why a Bowker ISBN is worth $125
Three reasons. First, you own it; it does not tie your book to any platform. Second, the metadata reads as professionally published. Third, you can use the same ISBN if you change print providers (move from KDP print to IngramSpark, for example) instead of needing a new identifier.
The $125 pays back the first time a bookstore considers your book and does not see “Independently Published” in their wholesale catalog.
You need a different ISBN per format
This catches every first-time author. Print paperback and print hardcover are different ISBNs. Ebook is a different ISBN (or no ISBN). Audiobook is a different ISBN (or an ACX-issued ID).
For a serious launch (print paperback + ebook), you need at least 2 ISBNs if you want one on the ebook (optional) and one on the print (required). That’s $250 in single ISBN purchases, or $295 for ten which gives you room for the hardcover, audiobook, and future editions.
What we do
We default to a 10-pack of Bowker ISBNs for clients launching a series, a single ISBN for one-off non-fiction, and an additional one if they want it on the ebook. The math is small money against the per-unit royalty over the life of the book.
What to skip
Don’t buy ISBNs from any reseller. Bowker is the official US agency; resellers exist and most are overpriced. Don’t take a free KDP-issued ISBN for a serious book unless your budget genuinely cannot absorb $125. Don’t share one ISBN across formats — that’s not how the system works.