WMA to M4B Converter
Processing entirely on your device — large files may take a moment.
WMA is Microsoft’s Windows Media audio format, still found in old music collections and voice recorders. 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 WMA compares to M4B
| WMA | M4B | |
|---|---|---|
| Compression | Lossy + Lossless variants | Lossy AAC + chapters |
| Quality | Respectable for its era | Speech-optimized bitrates |
| Compatibility | Windows-centric | Apple Books, Audible |
| Best for | Legacy Windows libraries | Chaptered audiobooks |
How to convert WMA to M4B
- 1
Select your files
Drag & drop your WMA 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 WMA format
WMA (Windows Media Audio) is Microsoft's MP3 competitor from 1999, best known for DRM-protected download stores in the 2000s. The family spans standard lossy WMA, WMA Pro (up to 24-bit/96 kHz) and WMA Lossless. On Windows it integrated seamlessly; everywhere else it required goodwill.
With Microsoft's own services having moved to AAC, WMA today is a conversion source: old music libraries and ripped CDs get converted to MP3/M4A/FLAC and the format is retired. WMA Lossless files should go to FLAC to preserve their losslessness.
+ Strengths
- ✓Native Windows playback and tagging
- ✓WMA Lossless preserves bit-perfect audio
! Limitations
- −Non-Windows support is poor
- −Ecosystem abandoned by its creator
- −DRM-legacy files may be unplayable
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 WMA to M4B?
Converting makes sense where the strengths of M4B meet what WMA cannot give you. Chapter markers survive on Apple platforms Meanwhile Non-Windows support is poor One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this WMA 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 WMA 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 WMA to M4B reduce audio quality?
If M4B is lossless, the output contains everything the WMA 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.