Publishing glossary
Publishing glossary
What is an ISBN, what does it cost, and do you need one?
An ISBN is a 13-digit book identifier that retailers, libraries, and distributors use to catalog your title. KDP issues one free for paperbacks, or you can buy your own to keep your imprint on record.
Checked:
✓ISBN-13 is the current format✓Free ISBNs exist on KDP✓Ebook and paperback need separate ISBNs
What an ISBN actually is
An ISBN (International Standard Book Number) is the 13-digit number that identifies one edition of one book in one format. Stores, libraries, and wholesalers order, catalog, and return copies by that number, which is how two books sharing a title never get mixed up.
It identifies the edition, not the author and not the words: a paperback and an ebook of the same manuscript carry different ISBNs, and a revised edition needs a new one. The same ISBN is printed twice in a paperback — as text on the copyright page and as the barcode on the back cover.
ISBN vs ASIN vs barcode
These three codes get used interchangeably in publishing forums, and they do different jobs. Amazon assigns an ASIN to every listing automatically, whether or not the book has an ISBN, which is why an ebook can sell on Kindle with no ISBN at all.
| Code | What it identifies | Where it is required |
|---|---|---|
| ISBN-13 | One edition in one format, globally | Print books sold through stores, libraries, and distributors |
| ASIN | One Amazon catalog listing | Every Amazon product page, including ebooks |
| EAN-13 barcode | The scannable image of your ISBN | The back cover of a printed paperback |
Free KDP ISBN vs buying your own
KDP offers a free ISBN for paperbacks, and the publisher of record on that number is Amazon. Buying your own ISBN from your national agency keeps you as the publisher of record, which matters if you want the same number accepted by IngramSpark, bookstores, or your own imprint page.
Fees differ by country and change over time: in the US Bowker sells a single ISBN for around $125 and a block of ten for around $295, while agencies in Canada and the UK issue them free to publishers. Confirm the current fee with your national agency before you buy a block.
Amazon ebooks do not need an ISBN at all. Buy one only if you plan to sell the ebook outside Amazon, such as through Apple Books or Kobo.
- Ebook ISBNs are not required on Amazon
- Each format needs its own ISBN
- An imprint name appears as publisher
Where the ISBN appears
The ISBN appears on the copyright page and as the EAN-13 barcode on the back cover. Keeping it consistent between your files and KDP metadata prevents listing errors.
How to read the 13 digits
An ISBN-13 is not a random string. It has a prefix (978 or 979 for books), a registration group for the country or language, a registrant for the publisher, a publication element for the title and format, and a final check digit. You do not need to decode it by hand to publish, but the structure explains why two formats cannot share one number.
The check digit is the part a validator can test immediately. If the checksum fails, the number was typed or scanned incorrectly. Use the free ISBN validator before you put the number on a cover, a copyright page, or a retail listing.
| Part | Job | What it means for authors |
|---|---|---|
| Prefix | Marks the product as a book | Usually 978 or 979 |
| Registration group | Country or language area | Assigned by the ISBN agency |
| Registrant | Publisher or imprint | The publisher of record |
| Publication | One edition in one format | A new format needs a new number |
| Check digit | Catches typing errors | Validate before publishing |
Where the number has to match
The same ISBN should appear in the KDP title setup, on the copyright page, and in the barcode on the back cover. A mismatch looks like a different edition to a retailer, a library, or a distributor, even when the words inside are identical.
If you use a free KDP ISBN, Amazon is the publisher of record. If you use your own, your imprint is. Decide before you design the copyright page or the back cover, because changing the publisher later means changing the number and the files.
- KDP title setup
- Copyright page
- Back-cover barcode
- Any retailer metadata feed
When you need a new ISBN
A new format needs a new ISBN: paperback, hardcover, and ebook are separate products. A revised edition with substantial content changes also needs a new number. A reprint with only a typo fix usually does not.
If you move from a free KDP ISBN to your own imprint, the publisher of record changes, so the book needs a new ISBN. Plan that before you publish a series, not after the first three titles are live.
Common ISBN mistakes
The most common mistakes are reusing an ebook ISBN for a paperback, printing the barcode at the wrong size, and letting the KDP metadata disagree with the copyright page. None of them are hard to fix before upload; all of them are annoying after a listing is live.
Check the number, the publisher name, and the format one last time before you export the cover and interior. The ISBN is small, but it is the identifier every other system uses to find the book.
FAQ
Frequently asked questions
Do I need to buy an ISBN for KDP?
Not necessarily. KDP provides a free ISBN for paperbacks. If you want your own publisher of record or plan to distribute outside Amazon, buy one from your country's ISBN agency.
How much does an ISBN cost?
It depends on your country. In the US, Bowker charges around $125 for a single ISBN and around $295 for ten; agencies in Canada and the UK issue them free. Blocks are cheaper per number than singles, which is why series authors buy ten.
Can I reuse one ISBN for ebook and paperback?
No. Every format and edition needs its own ISBN. Reusing one causes cataloging conflicts.
Does an Amazon ebook need an ISBN?
No. Amazon identifies ebooks by ASIN and accepts them without an ISBN. You only need an ebook ISBN to sell that ebook in stores outside Amazon.
Is the ASIN the same as the ISBN?
No. An ASIN is Amazon's own catalog code for a listing, and an ISBN is the publishing industry number for an edition. A paperback on Amazon has both.
Can I change the ISBN after publishing?
You can publish a new edition with a new ISBN, but you cannot silently swap the number on an existing listing. Treat the change as a new edition and update the metadata, cover, and interior together.
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