EPUB vs MOBI vs AZW3: which format to convert to
How EPUB, MOBI, and AZW3 differ, when to convert to each, and what an online conversion keeps or drops.
EPUB, MOBI, and AZW3 are all ebook containers. The readers that open them, and the layout they can keep, are not the same. Pick the wrong one and a Kindle may refuse the file, or the table of contents and images disappear after conversion.
What is each format for?
EPUB is an open standard. Apple Books, Kobo, Google Play Books, and most Android readers use it. Inside, it is XHTML plus stylesheets, so text reflows to the screen. That is what you want on a phone or an e-reader.
MOBI is the older Kindle format. Very old Kindles and some legacy import tools still read it. Complex layout, embedded fonts, and some styling are often simplified. Amazon also stopped accepting MOBI in Send to Kindle.
AZW3 (also called KF8) is the later Kindle format. Chapters, a table of contents, images, and basic styles usually survive better than in MOBI, and the result is closer to EPUB. If you copy a book onto a newer Kindle over USB, AZW3 is the better target.
AZW is an older Kindle package. You will see it on exports of older purchased books. It is not the same container as AZW3. Do not assume the two extensions behave alike. Convert them separately with AZW converter or AZW3 converter.
| Format | Better for | Layout |
|---|---|---|
| EPUB | Apple Books, Kobo, general readers | Reflowable, styles mostly kept |
| AZW3 | Newer Kindles over USB | TOC and images more intact than MOBI |
| MOBI | Very old Kindles | Basic; styling often simplified |
| Print, annotation, fixed pages | No reflow; hard to read on a small screen |
Which format should you convert to?
- Apple Books, Kobo, or a general reader: EPUB. Open EPUB converter.
- USB copy onto a newer Kindle, keeping the TOC and images: AZW3.
- A very old Kindle, or someone who explicitly asked for MOBI: MOBI, via MOBI converter.
- Print, annotation, or a fixed page design: stay on PDF. Forcing that into EPUB often scrambles columns and running headers.
If you are unsure, make two files: one EPUB and one AZW3. That fails less often than a single MOBI. Sending to a Kindle email address and copying over USB are different paths. See which format to send to Kindle.
What actually changes in a conversion?
Conversion does not rewrite the prose. It rebuilds the container. These are the usual surprises:
- Custom fonts may be replaced by the reader's system fonts.
- Columns, text boxes, and fixed headers or footers usually do not survive. EPUB and AZW3 are meant to reflow.
- A scanned PDF with no text layer becomes a stack of images. You cannot search it. Details are in PDF to EPUB.
- Store purchases with DRM cannot be converted. The file is encrypted, so there is no text to read. The extension does not matter.
If the source is Word or plain text, read Word and TXT to EPUB instead of exporting a complicated PDF first. FB2, common in Russian libraries and some Chinese catalogs, can be turned into EPUB with FB2 converter.
How do you convert a file here?
Open ebook converter, drop the file, choose the output format, and start. Conversion runs on the server. You do not install anything locally. The limit is 50MB per file, and each conversion uses 1 free quota credit. A text EPUB is usually quick. A large PDF can take several minutes. Keep the page open so you can download the result.
How do you convert one specific pair?
Once you know the target, use the page for that pair. Each one says when the conversion is worth it, how to run it here, and what you lose.
- EPUB to MOBI: only for a very old Kindle
- EPUB to AZW3: USB copy onto a newer Kindle
- MOBI to EPUB: move an old Kindle file to another reader
- AZW3 to EPUB: keep reading after you leave Kindle
- AZW to EPUB: an older package, not the same as AZW3
- EPUB to PDF: when you need fixed pages or print
- PDF to MOBI: fixed layout squeezed onto an old Kindle
- FB2 to EPUB: FictionBook into a general ebook
- HTML to EPUB: one web page into an offline book
- EPUB to TXT: the words only, no layout
Common questions
Which is more widely supported, EPUB or MOBI?
EPUB. Apple Books, Kobo, and most Android readers expect EPUB. MOBI is a legacy Kindle format, and Send to Kindle no longer accepts it.
Is AZW3 better than MOBI?
For Kindle, yes. AZW3 keeps chapters, a table of contents, images, and basic styling more faithfully. MOBI often simplifies them.
Does conversion rewrite the book?
It does not rewrite the author's text, but it repackages the file. Custom fonts, multi-column layouts, headers, and text boxes are often lost. A scanned PDF with no text layer usually becomes a series of pictures.
Keep reading
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