Amazon Ending Support For Mobi Files: What Changed And What To Use Now

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Amazon KDP no longer accepts MOBI files for new uploads or revisions, so you publish your ebook as an EPUB (or DOCX or KPF) instead. Books already published as MOBI stay on sale and need no action. Below are the dates, what to do next time you update a book, and why EPUB is good news. For how a Kindle version works alongside your paperback, see does a Kindle version hurt paperback sales.

What did Amazon change about MOBI files?

KDP ended support for MOBI on reflowable ebooks on 1-Aug-21 and on fixed-layout ebooks on 18-Mar-25. The change applies to new uploads, meaning new ebooks and revisions of published ones, and “no action is required for previously published eBooks that are not being updated” (KDP MOBI support FAQ).

For ebooks, KDP asks for EPUB, DOCX or KPF files, and it accepts both EPUB 2.0 and EPUB 3.0 as long as they meet the Kindle Publishing Guidelines. Its older help pages still list MOBI among the suggested formats, so go by the FAQ above.

I was working with Edward, from New Mexico, on formatting his books. I had told him to save his files as MOBI, using Jutoh, which I recommended for formatting at the time. I now recommend Atticus. After the rules changed, he came back and asked what to do now that Amazon wouldn’t take MOBI.

Why did Amazon use MOBI in the first place?

MOBI was the format Kindles and the Kindle apps used for years. Other stores used formats that wouldn’t work on a Kindle without converting them first. I read all my books on a Kindle, or listen to them, so this mattered to me.

What do you do next time you update a book?

You format the file yourself, which is one reason I tell everyone to learn how. We change our books all the time, and we want to put them into a format Amazon accepts without paying someone else each time.

In Atticus you export the EPUB version of your book. The same file goes to Amazon and to the other stores. Before you publish, check the book in the KDP previewer. KDP’s other ebook options are a DOCX file or a KPF file made with Kindle Create, but EPUB is still my first choice because it is the format every store takes.

Which ebook formats does KDP accept now?

For reflowable ebooks, where the reader can change the text size, KDP accepts EPUB, KPF and DOC or DOCX files. KPF files are made in Kindle Create or Kindle Previewer. For fixed-layout ebooks, where the page layout stays as you designed it (children’s books are a common example), KDP accepts EPUB and KPF. KDP recommends EPUB for both kinds (KDP MOBI support FAQ, October 2026).

That page names two dates for MOBI. Reflowable books lost it on 1-Aug-21, and fixed-layout books lost it on 18-Mar-25. If you only learned about this when a MOBI upload failed, that is the likely reason.

What if you only have an old MOBI file?

Calibre, a free program for your computer, lists MOBI as an input format and EPUB as an output format, and its FAQ says it can convert every input format on its list to every output format (Calibre FAQ, October 2026). So a DRM-free MOBI can be turned into an EPUB. Check the result in the KDP previewer before you publish, because a converted file can lose formatting. My advice: page through the headings, the images and the table of contents first, since those are the parts I would check before anything else.

My advice: if you still have the original manuscript, export a fresh EPUB from your formatting tool instead of converting the old MOBI. You will get cleaner chapters and a working contents page.

The Calibre FAQ adds that Amazon will stop accepting MOBI files emailed to Kindle addresses and suggests you change the email format in Calibre to EPUB.

If you outsource formatting, ask the person for the EPUB file and the source document. Then you can fix a typo next year without paying again, and you are not stuck with a format that a store may drop later. Ebooks keep being revised, and a source file you own makes each revision a ten-minute job. My team formats books too, and I check each one before it goes back: a KDP- and IngramSpark-ready EPUB from $67, within 3 business days of getting your manuscript. See book formatting

Why is EPUB good news?

EPUB is the same format Lulu, IngramSpark and Draft2Digital use. I recommend Draft2Digital because it spreads your book across as many platforms as possible. Before, you made two formats, MOBI and EPUB. With a good tool that was one more click. Now you export one file.

Amazon also added EPUB to Send to Kindle in 2022, so readers can send an EPUB to a Kindle without converting it first (TechRadar). Send to Kindle converts the EPUB into Amazon’s own format, and it doesn’t work on DRM-protected files from other stores.

If you have a Kindle book you want as an EPUB, read how to convert Kindle books to EPUB. For the full steps from file to published book, see how to self-publish your first book. Amazon changes things often, and that is why I wrote about the biggest Amazon KDP secret.

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