What is a .azw3 file?
Kindle Format 8 (KF8) · eBook · Amazon · 2011
AZW3, also called Kindle Format 8, is Amazon's eBook format for Kindle and the successor to MOBI. It supports modern styling and reflowable text, and it is tied to the Kindle ecosystem, so it opens best in a Kindle app or through Calibre.
What is a .azw3 file used for?
AZW3 replaced the old MOBI format on Kindle, adding proper CSS styling, embedded fonts and better layout while keeping the reflowable text that makes eBooks adapt to any screen.
Books bought from the Kindle Store usually carry DRM that ties them to your Amazon account, so they open only in Kindle apps signed in to that account.
DRM-free AZW3 files open in Calibre, which also converts them to and from EPUB. Amazon now accepts EPUB directly through Send to Kindle, converting it on the way in.
How to open a .azw3 file
The .azw3 format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Kindle app
- Calibre
macOS
- Kindle app
- Calibre
Linux
- Calibre
- Foliate
Web
- Kindle Cloud Reader (for purchased books)
How to convert a .azw3 file
You can convert a .azw3 file to EPUB, PDF, MOBI using a conversion tool or the export menu of an app that opens it.
.azw3 file signature (magic bytes)
Programs recognise a .azw3 file by the bytes at the start of the file, not by its name. These are the signatures for AZW3.
| Hex signature | Offset | Note |
|---|---|---|
| (no fixed signature) | 0 | PDB-based (Palm Database) container in the Mobipocket lineage; not reliably distinguished from MOBI or AZW by magic bytes alone |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .azw3 file?
AZW3, also called Kindle Format 8, is Amazon's eBook format for Kindle and the successor to MOBI. It supports modern styling and reflowable text, and it is tied to the Kindle ecosystem, so it opens best in a Kindle app or through Calibre.
How do I open an AZW3 file?
Read it in a Kindle app, or open a DRM-free one in Calibre. Books bought from Amazon are tied to your account and open only in Kindle apps signed in as you.
How do I convert AZW3 to EPUB or PDF?
Use Calibre: add the file and convert it to EPUB or PDF. This works for DRM-free files; books still protected by Amazon's DRM cannot be converted.
Related formats
Sources
Details on this page were checked against authoritative references: