M4B Converter
Free M4B converter that runs entirely in your browser. No upload, no signup — convert to M4B or from M4B into 200+ supported formats in one click.
Drop any file here or click to browse
All file types supported
About M4B
M4B
M4B is an MPEG-4 audio container variant specifically designed for audiobooks. It is identical to M4A in structure but supports chapter markers and bookmarking so players can resume playback. M4B is commonly used by iTunes and Apple Books.
- Developer
- Apple
- Initial release
- 2003
- Compression
- Lossy or lossless
- Color depth
- up to 24-bit
- Transparency
- No
Best for
- Distributing audiobooks with chapters
- iTunes and Apple Books audio
- Bookmarkable spoken-word content
- Long-form audio with navigation
- Resumable podcast delivery
Pros
- +Supports chapter markers and bookmarking
- +Resumes playback across devices
- +Identical audio quality to M4A
- +Recognized by iTunes and Apple Books
Cons
- −May carry FairPlay DRM
- −Less universal than plain MP3
- −Primarily Apple-ecosystem format
- −Some players ignore chapter markers
How to convert with the M4B converter
- 1
Choose the M4B file you want to convert from your PC, Mac or mobile device, or simply drag and drop it onto the page.
- 2
When your file is uploaded, the output format is preset to M4B. You can add more files to batch-convert them together.
- 3
Click the gear icon and tweak codec, quality, resolution or other options if you need them, then apply to all files if you want.
- 4
Click the Convert button. When conversion completes, download the result to your computer or save it back to Google Drive / Dropbox.
Frequently Asked Questions
What is an M4B file?▼
M4B is Apple's audiobook format — AAC audio with chapter markers and playback position memory, so long books resume where you stopped.
Why convert M4B to MP3?▼
Many players and Android apps cannot handle M4B or lose the chapter support. Converting to MP3 makes audiobooks playable on any device.
Will converting M4B keep the chapters?▼
MP3 does not support chapter markers, so the book becomes one continuous file. Keep the M4B original if you listen in Apple Books or a compatible app.
M4A vs M4B — what is the difference?▼
Both are AAC in an MP4 container; M4B is flagged for audiobooks with bookmarking and chapters. Players treat them differently based on that flag.
Are my audiobooks uploaded when converting?▼
No. Conversion runs locally in your browser — purchased or personal audiobooks never leave your device.
Supported Conversions
Specific converters
100% Free
No hidden fees, no subscriptions, and no limits. Enjoy complete access to all features gratis.
No Signup Required
Start converting immediately without creating an account or sharing email address.
Private & Secure
Your files never leave your device. All processing is completed locally for maximum privacy.
Batch Conversion
Convert multiple files simultaneously to save time. Fast and efficient multi-file queue.
Runs in Browser
Utilizes advanced client-side WebAssembly technology to process files directly inside your tab.
200+ Formats
Supports a wide variety of formats including images, documents, audio, video, and more.
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