M4B
- Lossy
- Audiobooks
- Keeps chapters
An audiobook file: the same AAC sound as an M4A, marked as a book so apps like Apple Books keep your place and show its chapters. Made for long spoken audio rather than music.
All tools
M4B Converter
Convert M4B files to MP3, WAV, FLAC and more in your browser — nothing is uploaded.
MP3, WAV, FLAC, M4A, M4B, MP4, AAC, OGA or WEBA, one or many. Drop them here or paste with ⌘V / Ctrl+V. Choose what each becomes on its row.
Runs on your device. Files are read and converted in your browser and aren't uploaded.
Learn more about M4B files
An M4B is lossy. Into WAV and FLAC its sound is kept exactly as it is now, in a bigger file (it can't get back what was lost); into another lossy format it's encoded again, so choose a bitrate at least as high as the original's.
- Into M4A, MP4 and AAC its AAC sound is copied as is when it can be — no re-encoding, no quality lost, and no encoder needed, so it works in Firefox too.
- Its chapters are kept when it becomes an M4B or M4A; every other format drops them.
- M4B files can be up to 2 GB.
- Making M4A, MP4, M4B or AAC needs the browser's AAC encoder (Chrome, Edge and Safari — not Firefox yet); OGA and WEBA its Opus encoder; MP3, WAV and FLAC are made in any modern browser.
How to do it
- Choose your M4B files, or drop them on the page — as many as you like.
- Each starts as an MP3; pick another format for every file with Convert to in Settings, or for one file on its row.
- Convert all, then download each file, or all of them in one .zip.