Free online M4B to ALAC converter

Source format: M4B

M4B is an AAC-based audiobook container commonly used by Apple devices, iTunes, and audiobook apps. It is very similar to M4A, but it is typically used for spoken-word content and often includes chapter markers, bookmarks, and sometimes metadata such as cover art and track information. M4B files are popular for audiobooks because they let listeners resume playback where they left off.

Target format: ALAC

ALAC stands for Apple Lossless Audio Codec. It is a lossless audio format designed to preserve the original audio quality while still compressing the file size. ALAC is widely supported in Apple ecosystems and is useful when you want archival-quality audio without the size of uncompressed PCM formats. It is commonly used for music libraries, long-term storage, and high-quality playback on Apple devices.

How to perform the conversion

The most reliable way to convert M4B to ALAC is with FFmpeg, because it can read audiobook containers and re-encode the audio to Apple Lossless while preserving metadata as much as possible.

1. Install FFmpeg on your computer.
2. Open a terminal or command prompt in the folder containing the M4B file.
3. Run a conversion command such as ffmpeg -i input.m4b -c:a alac output.m4a.
4. If the file contains multiple streams or chapters, FFmpeg will usually keep the main audio track and may preserve chapter data depending on the source and container support.
5. Check the resulting file in an audio player that supports ALAC, such as Apple Music, iTunes, VLC, or compatible mobile apps.

If you prefer a graphical workflow, you can also use desktop audio tools that support export to Apple Lossless, but support for audiobook-specific features is often limited. For a quick browser-based option, you can convert the file on 101convert.com for free without installing any software.

Notes on quality and compatibility

M4B to ALAC is not a lossless restoration if the source M4B already contains AAC audio, because AAC is a lossy codec. Converting it to ALAC will preserve the current decoded audio in a lossless container, but it will not recover audio detail lost during the original AAC encoding. This means the output may be larger than the source while sounding essentially the same.

Another important limitation is that chapter markers and audiobook navigation features may not always survive a conversion, depending on the tool and output container. If chapters are important, test the result in your target player. Also note that ALAC is usually stored in an .m4a file extension, even though the codec is ALAC; some players may not recognize .alac as a standard extension.

For best compatibility, keep the output as .m4a with ALAC audio, and verify playback on the devices or apps where you plan to use it.