FormatDrop
How-To Guide

How to Convert M4B to MP3

M4B is Apple's audiobook format with chapter markers and bookmarking metadata. M4B files play natively in Apple Books on iOS/macOS. Converting to MP3 lets you play audiobooks on any device — Android media players, car stereos, Bluetooth earbuds, and any generic MP3 player — without Apple's ecosystem.

Open M4B to MP3 Converter

Step-by-step instructions

  1. 1

    FFmpeg — single file conversion

    Convert entire M4B to one MP3: `ffmpeg -i audiobook.m4b -c:a libmp3lame -q:a 2 output.mp3`. -q:a 2 uses LAME VBR ~190 kbps — good quality for audiobooks. For fixed bitrate: `-b:a 64k` (perfectly fine for speech, ~30 MB/hour). Chapter markers are lost in single-file MP3.

    Go to converter
  2. 2

    m4b-tool (purpose-built, recommended for chapters)

    m4b-tool creates one MP3 per chapter: `composer global require sandreas/m4b-tool && m4b-tool convert --audio-format mp3 --audio-bitrate 64k audiobook.m4b`. Requires PHP and FFmpeg. Creates a folder with one properly-named MP3 per chapter. Available on Mac, Linux, and Windows.

  3. 3

    Apple Music / iTunes on Mac (simplest GUI)

    Select the M4B tracks in the Music library → File → Convert → Create MP3 Version. Music creates a single-file MP3. For chapter-split MP3: use m4b-tool. The iTunes method uses Apple's AAC-to-MP3 transcoder — good quality at 256 kbps.

  4. 4

    FFmpeg chapter split (advanced)

    Get chapters: `ffprobe -print_format json -show_chapters audiobook.m4b > chapters.json`. Extract by time: `ffmpeg -i audiobook.m4b -ss 0 -to 2340.5 -c:a libmp3lame -q:a 4 chapter_01.mp3`. Repeat for each chapter using the start/end times from the JSON output.

Why convert M4B to MP3?

M4B is Apple's walled garden for audiobooks. MP3 plays on every device without proprietary software — the right format for listening anywhere.

Your files never leave your device

FormatDrop runs the conversion engine entirely inside your browser using WebAssembly. No file upload. No server. Nothing stored. You can verify this by opening DevTools → Network tab and watching: zero upload requests.

Frequently asked questions

Do chapter markers survive M4B to MP3 conversion?
Not in a single-file MP3 — MP3 doesn't natively support chapters in a widely compatible way. Split by chapters using m4b-tool or FFmpeg to preserve chapter structure as individual MP3 files. ID3v2 chapter tags exist but are supported only in specific players.
What bitrate should I use for audiobook MP3?
64 kbps for speech is perfectly adequate — audiobooks don't need the frequency range of music. 64 kbps mono MP3 is indistinguishable from higher bitrates for narration. A 10-hour audiobook at 64 kbps is approximately 288 MB. Use 32 kbps for maximum storage savings (still clear speech).
Can I play M4B files on Android?
Yes with Smart AudioBook Player, ListenUp, or BeyondPod. The built-in Android music player usually doesn't recognize M4B. If your audiobook player doesn't support M4B, convert to MP3 (split by chapters) using m4b-tool — the split files import cleanly into any audio player.
Convert M4B to MP3 Now — Free

No account. No upload. Works in any browser.

More guides

How to Convert HEIC to JPGHow to Convert PNG to PDFHow to Convert MOV to MP4How to Convert WebP to JPG