How to use the EPUB to AZW3 converter
- Add your DRM-free EPUB files.
- Convert to AZW3.
- Connect the Kindle, drag the .azw3 files into the documents directory and eject; the books then appear in your library.
Why AZW3 for USB transfer
Stylesheets, embedded fonts, tables, floating pictures and multi-level contents all work in AZW3, while MOBI 6 supports none of them. Kindle readers from the Paperwhite onwards and the Kindle apps open it natively.
Send to Kindle converts EPUB on Amazon’s side, so AZW3 matters mostly for cable sideloading, for calibre libraries and for a Kindle that has never been linked to Amazon.
On the device
The cover, title, author and chapters display like a store purchase, and the Kindle’s font and size controls still work. Fonts embedded in the EPUB come along and show up as the Publisher Font option.
Sideloaded books are not in your Amazon cloud library, so reading position and highlights do not sync between devices.
Upload and deletion
calibre performs the conversion on our server, so each EPUB is sent over HTTPS and processed in a sandbox without network access.
The EPUB and AZW3 are deleted right after the converted file is returned. Keep your EPUB originals: they are the better master copies for future devices.
Questions
Will the Kindle show the book cover?
Yes. The cover from the EPUB is written into the AZW3, so the book shows its own artwork on the Kindle home screen instead of a plain placeholder.
Can I convert a book with DRM?
No. DRM-protected EPUBs from stores are encrypted and are refused with an error message. Books from Project Gutenberg or bought DRM-free convert normally.
Does Send to Kindle take AZW3?
No, Send to Kindle refuses AZW3. Email the EPUB itself, or copy the AZW3 over USB.
Can I convert a whole series?
Yes. Add every EPUB, convert, download the ZIP and copy all the AZW3 files at once. The Kindle indexes them after you eject it.