MOBI was the e-book format of the Kindle's first decade, and many personal libraries still hold hundreds of .mobi files from that time. Today the open EPUB format is the one almost everything reads, including Amazon's own Send to Kindle service. Converting a MOBI to EPUB is one of the cleaner e-book conversions, because both formats are built on HTML underneath. The limits come mostly from what the old MOBI file contained in the first place.
Why convert MOBI to EPUB
- Send to Kindle no longer takes MOBI. Amazon started accepting EPUB in 2022 (by e-mail first, in the Kindle mobile apps from August 2022). It then wound down MOBI from 1 November 2023 and ended Send to Kindle support for .mobi, .azw and .prc by 20 December 2023. To get an old MOBI onto a new Kindle wirelessly, send it as EPUB.
- Switching to another reader. Kobo, PocketBook, Tolino and Apple Books read EPUB but not MOBI.
- Editing. EPUB is a ZIP of XHTML and CSS, so fixing a typo or replacing the cover is easy with any EPUB editor.
- Long-term storage. EPUB is an open W3C standard; MOBI was only partly documented.
What our converter keeps and what it cannot
Our converter reads classic MOBI files as well as the newer KF8 variant. The result is an EPUB 2 file. Files with the older .prc extension are handled the same way, since they are the same format.
| Content | In the EPUB |
|---|---|
| Text, headings, bold and italics | Kept |
| Table of contents and chapter links | Kept as EPUB navigation |
| Images and cover | Kept, at the resolution stored in the MOBI |
| Title, author, publisher, language | Kept as EPUB metadata |
| Your highlights, notes and reading position | Not in the .mobi file, so not transferred |
| Kindle features (X-Ray, Popular Highlights) | Amazon services, not part of the file |
One technical detail matters. In 2011 Amazon introduced KF8 (Kindle Format 8, later known as AZW3), which supports modern CSS and embedded fonts. Many .mobi files from that time are "joint" files that carry both the old Mobipocket 6 version and a KF8 version. Our converter reads the KF8 part when it is present, so you get the richer formatting. A file with only the old format has very limited styling, and the EPUB will look just as plain; conversion cannot add design that was never there.
DRM: what we can and cannot convert
Books bought in the Kindle Store and downloaded to a computer are protected by Amazon's DRM, and so were many MOBI files from older shops. Our converter refuses encrypted files, and we do not remove DRM. That is a legal line as well as a technical one. Newer Kindle downloads in KFX format and old Topaz books are not supported at all. DRM-free MOBI files convert normally: books from Project Gutenberg and similar libraries, files you created yourself, and purchases from shops that sell without DRM or with only a watermark.
Common problems and fixes
"MOBI won't open on Kobo" or "on my phone"
Kobo and most reading apps outside Amazon do not support MOBI. Convert to EPUB and copy the file to the device.
"Send to Kindle says the file type is not supported"
That is the MOBI shutdown from late 2023. Convert to EPUB and send that. If you prefer to keep the MOBI, copy it over USB into the Kindle's documents folder; Kindle devices still read MOBI.
"Strange characters after conversion"
Some old MOBI files, typically made with amateur tools, declare the wrong text encoding in their header. Accented letters then come out garbled, especially in Central European languages. The free calibre app for your computer has an input encoding option that overrides the declared one.
"The EPUB has a different font"
Unless the book embedded its own fonts (possible only in KF8), the reading device chooses the font, as it did on the Kindle.
Format background
MOBI comes from the French company Mobipocket, which released it in 2000. Amazon bought Mobipocket in 2005 and based the first Kindle format on it. The Library of Congress description notes that the format was only partly documented and that most commercial MOBI books carried DRM. EPUB was published by the IDPF in 2007, revised as EPUB 3 in 2011 and is now maintained by the W3C as EPUB 3.3; see also the EPUB description.
Alternatives
If you only read on a Kindle and copy books over USB, you do not need to convert anything. For a large library, the free calibre app converts in bulk and keeps your collection organised. Our converter is handy for a few files without installing anything, works on a phone and takes up to 10 files at once, with the results as a ZIP. Need a printable version instead? See EPUB to PDF.