ALAC to M4B Converter
Processing entirely on your device — large files may take a moment.
ALAC is Apple's lossless codec inside an MP4 container — the iTunes Store lossless tier and every big iOS recording. Converting M4B to MP3 frees audiobooks to play on car stereos, dumb players and anything without chapter support.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How ALAC compares to M4B
| ALAC | M4B | |
|---|---|---|
| Compatibility | iOS, macOS, iTunes, ffmpeg | Apple Books, Audible |
| Best for | Apple-ecosystem lossless libraries | Chaptered audiobooks |
How to convert ALAC to M4B
- 1
Select your files
Drag & drop your ALAC files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to M4B". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted M4B file individually, or grab everything at once as a ZIP archive.
About the ALAC format
ALAC (Apple Lossless Audio Codec) is Apple's FLAC equivalent: bit-exact lossless compression inside an MP4 container, opened-source in 2011 and now native on every Apple device and most server-side pipelines. It is what iTunes Store sells as "lossless" and what iPhone recordings encode to by default.
For non-Apple players FLAC is the safer target, and conversion is sample-exact in both directions — the decode is handled by ffmpeg's native ALAC decoder without any Apple runtime.
+ Strengths
- ✓Native on every Apple device
- ✓Open source since 2011
- ✓Reasonable sizes inside MP4
! Limitations
- −Outside Apple ecosystems FLAC wins
- −Slightly worse ratios than FLAC
- −Confusing .m4a extension doubles as lossy
About the M4B format
M4B is M4A wearing an audiobook badge: the same AAC audio in an MP4 container, plus chapter markers that Apple Books and Audible apps render as a scrubbing timeline. Buy an audiobook outside Audible and it likely arrives as M4B.
The format is deliberately chained to Apple's book ecosystem. Converting M4B to MP3 sets the book free: car stereos, gym players, old iPods and every app without chapter support will play it — though the chapter marks themselves are flattened away.
+ Strengths
- ✓Chapter markers survive on Apple platforms
- ✓Efficient AAC audio
! Limitations
- −Chapters vanish in MP3 conversion
- −Non-Apple support is patchy
Why convert ALAC to M4B?
There is a concrete reason this conversion exists: Outside Apple ecosystems FLAC wins M4B sidesteps that — Chapter markers survive on Apple platforms If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this ALAC to M4B converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for ALAC to M4B?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.
Will converting ALAC to M4B reduce audio quality?
If M4B is lossless, the output contains everything the ALAC file contains — no further loss is added. If M4B is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.