If you’ve read this far, you’re probably a self-published author who has once struggled with Amazon’s fussy Kindle Direct Publishing platform. The platform, which allows you to upload and sell ebooks and paperbacks, has always been unusually frustrating when it came to ebook layout. If you did it right, you were fine. If you did it wrong, things went bad pretty quickly.
Why would they go bad? Because KDP ostensibly accepted many popular formats—namely, epub and mobi—you could lay out a book in a desktop publishing app, export it, and then upload it to KDP. The result? A final ebook either looked fine or, more likely, looked like a ransom note thanks to bad fonts and paragraph spacing or flaws that made your book look like an easy reader for grade-schoolers, with huge fonts and broken chapters.
So here’s what Amazon’s doing: If you want to create “reflowable” books, i.e. books that work on many devices and automatically fit the page, you can’t use the most problematic format of all, mobi. According to a user on the mobi support forum, KDP customer support sent the following message:
We listened to your feedback and are making it simpler to publish eBooks on Kindle. Starting June 28, 2021, we will no longer support files in MOBI, PRC or AZK formats when publishing new reflowable eBooks or updating the content for previously published eBooks. Instead, we ask publishers to use EPUB, KPF (Kindle Create files), or DOC/DOCX (Microsoft Word files) files for reflowable eBooks. Please note MOBI files are still accepted for fixed-layout eBooks.You don’t need to take any action for reflowable eBooks already published unless you are updating the eBook files.
Amazon’s instructions for uploading ebooks to KDP now notes that “MOBI is no longer support for reflowable content.”
This means you can still upload a mobi file if you want to suffer from crazy formatting on some Kindle devices but that Amazon recommends using its own file format, KPF, or the slightly more forgiving epub format if you’re trying to stay platform agnostic.
The mobi file appeared in 2000 with the rise of Mobipocket, an early French ebook company. Like epub, the mobi is an XML-based file that is based on the legacy Open eBook Publication Structure (OEBPS) or Open eBook standard. The key word here is “legacy” because, given the slow pace of ebook evolution, most format standards are over 20 years old. The epub is actually a pure version of the Open eBook standard that has survived as long as mobi but with less wonkiness.
Anyway, that’s the bit of news about KDP formats, an important bit especially if you’re working on a three-book trilogy of sci-fi fantasy featuring a feisty wizard and her robotic sidekick.