Convert AZW3 to EPUB

AZW3 is the file format Amazon ships Kindle books in (internally called KF8). It's EPUB-adjacent — derived from the same source concepts — but wrapped in Amazon's packaging with an optional DRM layer that only Kindle devices and apps can unlock. If you want to read a Kindle purchase on a Kobo, Apple Books, or anywhere off the Amazon ecosystem, you convert to EPUB first.

Before you start: is your AZW3 DRM-locked?

Books purchased from the Kindle Store almost always carry DRM. Calibre and every mainstream converter will refuse to convert them — this is enforced, not a bug. Removing DRM is legal in some jurisdictions for books you own (personal backup), illegal in others (anti-circumvention laws). We don't cover DRM removal. If your AZW3 is DRM-free (side-loaded, public-domain, or explicitly DRM-free), continue below.

Method 1: Calibre (most reliable)

1. Install Calibre from calibre-ebook.com. Free, open source, Windows/Mac/Linux.
2. Drag your AZW3 into Calibre's library window.
3. Select the book → Convert books. Set output format to EPUB in the top-right dropdown.
4. Under EPUB Output, check "No default cover" if you want to keep the source cover, and "Preserve cover aspect ratio".
5. Click OK. Calibre adds the EPUB alongside the AZW3 in its library — right-click → Save to disk to export.

Calibre's AZW3 reader is the most mature — it handles KF8's CSS subset, typography hinting, and chapter structure better than most converters. The main gotcha: Calibre's default heuristics can mangle paragraph breaks in poorly-coded source files. If paragraphs look wrong, re-convert with Heuristic processing disabled.

Method 2: Online converters

Plenty of web-based AZW3 → EPUB converters exist. They're fine for DRM-free single files, but understand the trade-offs: you're uploading the full book to a third-party server, their retention policy may be "forever and indexed", and quality varies wildly (many silently corrupt the TOC or drop images). Stick to the three or four reputable ones — or just use Calibre, which runs locally and is free.

Method 3: Command line with KindleUnpack + Pandoc

For automation or batch conversion, use KindleUnpack to extract the raw content, then Pandoc to rebuild as EPUB:

python3 kindleunpack.py book.azw3 unpacked/
pandoc unpacked/mobi7/*.html -o book.epub --metadata title="Book Title"

Cleaner than Calibre for books that already have well-structured HTML inside. Worse for complex Kindle-specific formatting.

After conversion: clean up

AZW3 → EPUB conversions commonly leave artefacts. Run the output through:

• EPUB Validator — catches broken references, duplicate IDs, missing mimetype. Common after KF8 conversion.
• Metadata Editor — fix title, author, cover. Amazon's metadata tags sometimes don't map 1:1 to EPUB fields.
• EPUB Compressor — AZW3 uses different image compression; converted EPUBs are often 30–50% larger than necessary.

Reading the result

The converted EPUB will open on every major ereader except Kindle itself (Kindle since 2022 accepts EPUB only via Send-to-Kindle, which converts it back to KF8 on Amazon's side). See the device guides for Kobo, iPhone/iPad, and Android.

Related

• Convert EPUB to AZW3 — the reverse direction
• Send EPUB to Kindle — the 2022+ way
• EPUB vs MOBI — why Amazon deprecated MOBI
• EPUB Validator — verify converted output