Authors who have already grasped that an ISBN identifies a specific edition, not the book in the abstract, often still get tripped up on the practical question of formats: does the ebook really need a different number from the paperback? The short answer is generally yes, but the fuller picture depends on which platform is publishing the ebook, and it is worth walking through properly rather than assuming a single rule covers every case.
Why formats differ
An ISBN exists to let trade, retail and library systems identify precisely which product they are dealing with. A paperback and an ebook of the same underlying text are different products in every practical sense: they are bought, delivered, priced, reviewed and returned differently, and a retailer or distributor needs to be able to tell them apart in its own systems. This is the underlying reason formats are generally treated as separate publications for ISBN purposes, rather than an arbitrary rule imposed for its own sake.
Paperback
A paperback edition, whether distributed through Amazon KDP’s free ISBN option or a purchased ISBN for wider trade distribution, generally has its own identifier separate from any ebook or hardback edition of the same book.
Hardcover
A hardcover edition, likewise, is generally treated as its own distinct publication, separate from both the paperback and the ebook, and typically needs its own ISBN if it is being formally distributed as its own product.
Ebook
Ebook ISBN requirements genuinely vary by platform, more so than print formats do, and this is the area where blanket claims cause the most confusion. This is not a case where a single universal answer exists; it depends on the retailer or distributor in question, and their current published requirements.
Kindle
At the time of writing, Amazon KDP does not require an author-supplied ISBN for a Kindle ebook, and instead assigns its own ASIN automatically. This means many authors publishing exclusively on Kindle never obtain a separate ISBN for that specific ebook edition at all, relying on the ASIN as its identifier within Amazon’s own systems.
EPUB distributed widely
Where an ebook is being distributed as an EPUB file to multiple retailers beyond Kindle, through a wide ebook distributor or directly to individual retailers, an ISBN is more commonly expected, since the distributor or retailer needs a consistent identifier that works across its own catalogue rather than relying on a Kindle-specific ASIN, which is not recognised outside Amazon. Check the current documentation of whichever wide ebook distributor or retailer you plan to use to confirm their exact requirement.
Audiobook
An audiobook edition, where produced, is generally treated as yet another distinct format from print and ebook editions, with its own identifier conventions that vary by audiobook platform, as covered in our related guides on ISBN requirements.
Revised editions
If a book is later revised with substantive content changes, each format affected by the revision, whether paperback, hardback or ebook, is generally treated as a further distinct publication from the original edition, potentially needing its own new identifier separate from both the original edition’s ISBN and the identifiers used for other formats. For example, a non-fiction author who releases a substantially revised second edition, in both paperback and ebook, would typically need to treat the second-edition paperback and second-edition ebook as two more new, distinct publications, on top of the two identifiers already used for the first edition.
Multiple ebook formats, where relevant
In some cases, an author distributing an ebook through several different platforms may end up using more than one identifier for what is, in substance, the same ebook content: an ASIN for the Kindle edition and a separately obtained ISBN for a wider EPUB distribution, for instance. This is a common and reasonable setup, not a mistake, provided the metadata across each listing accurately reflects the same book, so readers and retailers are not confused about what they are looking at.
ISBN planning across formats
| Format | Typical identifier approach |
|---|---|
| Paperback (KDP only) | Free KDP-assigned ISBN, or your own purchased ISBN |
| Paperback (wider trade, e.g. IngramSpark) | Your own purchased ISBN, generally required |
| Hardcover | Its own identifier, separate from the paperback |
| Kindle ebook | Amazon-assigned ASIN, ISBN not generally required |
| EPUB distributed widely | An ISBN is more commonly expected |
| Audiobook | Varies by platform; some use their own internal identifiers |
This table sets out a typical pattern at the time of writing, not a fixed or permanent rule. Platform requirements change, and the only reliable way to confirm what applies to your book is to check the current documentation for each specific platform before you publish.
KDP
Within Amazon KDP itself, a paperback and a Kindle ebook of the same book are set up as two separate listings in the KDP dashboard, with their own identifiers (a free or purchased ISBN for the paperback, an ASIN for the Kindle ebook), even though KDP links them together on the Amazon product page as "available formats" for the reader’s convenience.
IngramSpark
On IngramSpark, print formats such as paperback and hardback are each set up as separate titles with their own ISBNs, and any ebook distribution offered through IngramSpark at the time you check would similarly be expected to carry its own identifier, distinct from the print editions.
Metadata consistency across formats
Even though each format generally carries its own identifier, keeping the title, subtitle, author name, series information and description consistent across every edition and platform is genuinely important. Inconsistent metadata between a paperback and an ebook listing of the same book, such as a slightly different subtitle or an outdated author bio, can confuse readers and make the two editions harder for retail systems to correctly associate as related products.
Keeping formats consistent
- Use the same title, subtitle and series information across every format and platform.
- Keep the author name spelled identically everywhere.
- Update the description on every listing when you make a meaningful change to one.
- Record which identifier (ISBN or ASIN) belongs to which exact format, in one master document.
- Recheck each platform’s current ISBN requirement before adding a new format or distributor.
Common mistakes
- Trying to reuse one ISBN across formats. Using the same ISBN for both a paperback and an ebook can cause retail and cataloguing systems to treat two different products as one, creating listing errors.
- Assuming ebook rules match print rules. Ebook ISBN requirements vary meaningfully by platform, unlike print formats, where the pattern is more consistent.
- Forgetting the ASIN is not portable. A Kindle ASIN only works within Amazon’s own systems and cannot substitute for an ISBN when distributing an ebook more widely.
- Letting metadata drift between formats. Inconsistent titles, subtitles or descriptions between a paperback and ebook listing of the same book can confuse readers and retail systems alike.
- Not planning for a future revised edition. Failing to anticipate that a substantive revision will need new identifiers across formats can cause confusion when that day comes.
Frequently asked questions
Can I use the same ISBN for my paperback and ebook?
Generally no. Formats are usually treated as separate publications, each typically needing its own identifier where one is required.
Does my Kindle ebook need an ISBN?
At the time of writing, generally no; Amazon assigns its own ASIN for Kindle ebooks instead.
Does a wide EPUB distribution need an ISBN?
It is more commonly expected than for Kindle-only publishing, though the exact requirement depends on the specific distributor. Check their current documentation.
Do I need a new ISBN if I revise my ebook slightly?
Minor corrections generally do not require a new identifier. A substantive revision, treated as a new edition, generally does.
Should the title and description match exactly across paperback and ebook listings?
Yes, keeping metadata consistent across formats helps readers and retail systems correctly recognise them as editions of the same book.