EPUB → MOBI/AZW3
Converting a novel from EPUB (.epub) to Kindle / Mobipocket (.mobi, .azw3, .azw) is a routine step in practice — the Kindle format reads natively on Amazon devices and apps, and can be delivered with Send to Kindle. Fortunately EPUB and Kindle / Mobipocket are structurally close, so there is not much to lose. Below we explain in detail how EPUB becomes Kindle / Mobipocket and what to watch out for, and the page ends with a converter that does the job right in your browser — nothing is uploaded, the file never leaves your machine.
What is EPUB?
EPUB is the most portable e-book format outside the Kindle ecosystem. It is really a ZIP archive holding XHTML content, CSS, images and a manifest that fixes the reading order. Because content and presentation are stored separately, the same file re-lays-out itself for a phone, a tablet or a desktop, and the reader can change the font size at any time. The table of contents, cover, title and author all have standard places, so library software recognises and sorts the book correctly. For text-heavy fiction, EPUB is usually the safest format to distribute and to keep long term. Read the EPUB format guide
| Extensions | .epub |
|---|---|
| Typical use | Mainstream e-book distribution and long-form reading, especially text-heavy books such as novels. |
What is MOBI/AZW3?
The Kindle family (.mobi, .azw3, .azw) is Amazon's proprietary e-book format. It reflows and can carry a table of contents, and it is read mainly on Kindle devices and the Kindle app, or delivered through Send to Kindle. AZW3 supports a reasonable amount of CSS while the older .mobi barely supports any. It is one of the most common proprietary formats in existing libraries — plenty of books bought or downloaded years ago are in it — which is why converting it to something more portable is such a practical need. Read the MOBI/AZW3 format guide
| Extensions | .mobi.azw3.azw |
|---|---|
| Typical use | Reading on Kindle devices and the Kindle app; one of the most common proprietary formats in existing libraries. |
How to convert EPUB to MOBI/AZW3
EPUB content is XHTML fragments plus separate CSS. Extraction must follow the OPF manifest's spine for reading order and its toc for navigation. Concatenating files in ZIP name order — the most common mistake when flattening an EPUB to a single TXT — scrambles the chapters.
Producing .mobi/.azw3 requires Amazon's toolchain or Calibre. AZW3 supports reasonable CSS while legacy .mobi supports very little; for newer devices, target AZW3 — or simply deliver an EPUB.
Convert EPUB to MOBI/AZW3
EPUB → KINDLE
The Kindle formats (.mobi, .azw3, .azw) are Amazon's proprietary binary containers with no public specification, so they cannot be reliably parsed or produced in a browser. This direction needs a desktop e-book tool; the EPUB or TXT you convert can be read in the Kindle app directly.
A novel reader that syncs your progress across every platform
Tide Reader opens TXT and EPUB, detects chapters on import, lays the text out the way you like it, and syncs your reading position across Windows, macOS, iOS and Android. Drop the converted file in and start reading.
Download Tide ReaderTXT and EPUB; local-first reading, with optional cloud sync and WebDAV.