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Ebook File Details: EPUB, Kindle EPUB, MOBI, and PDF

In the old days, MOBIs were for Kindles and EPUBs were for everything else.

Now that Amazon Send to Kindle will accept EPUB files, readers are reporting ugly formatting when they send EPUBs to their @kindle accounts. We’ve added Kindle EPUB delivery to solve this problem!

Accepted File Types

When you upload your ebook to BookFunnel, you can upload between one and four ebook files per book: Generic EPUB, Kindle EPUB, Legacy MOBI, and PDF.

Uploading your ebook files is as simple as dragging-and-dropping them onto your book on the BookFunnel dashboard.

Screenshot of book details view on the BookFunnel dashboard


Your Generic EPUB will be distributed to any non-Kindle app, including Apple Books, Kobo, NOOK, and Play Books. If you use Vellum to create your books, please export a Generic EPUB. Store-specific EPUBs can be broken when opened in the wrong reading app, but the Generic EPUB functions in any non-Kindle reading app.


When you send an ebook to Send to Kindle, Amazon converts it to their own format and then delivers it to your Kindle (or Kindle app). Sometimes the converted file looks very different than the book you emailed to Send to Kindle.

To improve these conversions, BookFunnel will now distribute a special Kindle EPUB file for Kindle readers. A Kindle EPUB is an EPUB with Amazon-friendly formatting that is more likely to convert cleanly with Send to Kindle. We never want readers to send your books to their Kindle apps and the entire book be in italics (**shudder**).

  • Vellum Authors Upload your Kindle EPUB and BookFunnel will ship your Kindle EPUB when a reader wants to email a book to their Send to Kindle account. Vellum authors should always upload both your Generic EPUB and your Kindle EPUB so that your books look beautiful everywhere! Learn how to export your Kindle EPUB and Generic EPUB.
  • Atticus Users When you upload your EPUB, BookFunnel will automatically create a Kindle EPUB for your Kindle readers. You can disable the Kindle EPUB if you are dissatisfied with the conversion. Please note: Atticus EPUBs can include styling that Send To Kindle will corrupt. You should email your Atticus EPUB to your @kindle account and view it on an iOS device to see if Send to Kindle bolded or italicized any chapters or sections.
  • All Other Ebook Software Users This Kindle EPUB setting is optional and disabled by default. Email your EPUB to your @kindle account to see how your ebook will convert! If Amazon italicizes or bolds your entire book, you should enable the Kindle EPUB. You can enable it by clicking the Action button next to the file type and BookFunnel will compile a Kindle EPUB from your Generic EPUB.


Amazon has deprecated MOBIs, but many readers are on legacy Kindles that can’t open an EPUB file. BookFunnel will offer MOBIs for direct download for readers on these devices:

  • Kindle ereaders like the Paperwhite, Voyage, Oasis, Touch
  • Kindle App on Mac and PC
  • Android Kindle App
  • Kindle Fires and Amazon Fire Tablets

If you do not upload a MOBI, BookFunnel will automatically create one from your Kindle EPUB or Generic EPUB.


PDF files are great for things like worksheets, coloring books, and graphic novels, and can be used for ebook files as well. PDF-only files are not ideal for ebook reading, as many people now read on their mobile phones. PDF files, unlike ebook files, don’t allow font or text size adjustment.

You’re not required to provide a PDF with your ebook, but some readers will appreciate it, especially if they read on their computer or like to print out books for reading (yes, really!).

Maximum File Size

The largest file you can upload to an author account is 30 MB*. But, many readers cannot accept email attachments larger than 10 MB, so your file should be smaller than that if possible. If it the file is too large, readers cannot send your book to their Send To Kindle @kindle account.

* If you are subscribed to our Mid-List plan (or higher), you can request a limit of 100 MB. BookFunnel cannot distribute ebooks larger than 100 MB.

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