Audio conversion
Convert M4B to AAC
M4B is the format audiobook and podcast apps use to store chapters and remember where you paused. AAC is a plain audio format that nearly everything else plays. To convert M4B to AAC, open the file in a converter and export it as AAC, which turns the book into one continuous audio track. Doing this on your own computer means the recording never leaves your machine.
All 2,748 conversions verified on macOS, Windows, and Linux against the shipping release, this one included. Every conversion runs entirely on your own computer.
- Extension
- .m4b
- Type
- Audio
- Typically
- Audiobooks, podcasts
- Compression
- Lossy
- Extension
- .aac
- Type
- Audio
- Typically
- Apple / streaming audio
- Compression
- Lossy
Convert M4B to AAC on your own computer. Nothing uploads.
One-time purchase, no subscription. 14 days to change your mind.
How to convert M4B to AAC
- Open Morphjet and drag in the M4B file, or a whole folder of audiobooks and podcasts at once.
- Choose AAC as the output format. This drops the chapter markers, since a plain AAC file can't hold them.
- Convert. The AAC file is written next to your original, and nothing leaves your machine.
M4B vs AAC: what actually changes
| M4B | AAC | |
|---|---|---|
| Chapter markers | Yes, split into chapters for navigation | No, plays as one continuous track |
| Remembers your place | Yes, most audiobook apps resume where you left off | No, treated like a regular song or track |
| Compatibility | Mainly audiobook and podcast apps | Very broad, plays on nearly any device, phone, or music app |
| File size | Compact, one file for a whole book | Similar size, sometimes a bit smaller without chapter data |
| Quality | Lossy, tuned for speech | Lossy, comparable quality for spoken word |
| Variable playback speed | Built in, most audiobook apps let you speed it up | Depends on the player, not tailored to audiobooks |
When to convert, and when not to
Convert M4B to AAC when you want to play an audiobook or podcast in a regular music app, a car stereo, or a device that doesn't recognize the M4B format.
Keep the M4B if you rely on chapter navigation or want your player to remember your exact place, since a plain AAC file drops both.
Why not just use an online converter?
An audiobook can say a lot about someone, from what they're reading to what they're studying for. An online converter means that file, and everything in it, sits on a server you don't control while it's processed. Converting on your own computer keeps the audiobook local the entire time, so nobody else ever has a copy of it to hold onto.
Questions
Does converting M4B to AAC lose audio quality?
Since M4B audio is usually already AAC-encoded speech, re-exporting it as AAC doesn't introduce a meaningful quality drop. What you do lose is the chapter markers and bookmarking, not sound quality.
Will I still have chapters after converting to AAC?
No. AAC is a plain audio format without chapter support, so the file plays start to finish as one track. If chapters matter to you, keep the M4B.
Can I convert a DRM-protected audiobook to AAC?
No. If an M4B is copy-protected, Morphjet can't convert it, the same as any other converter. This works on audiobooks and podcasts you own outright, without protection.
Does AAC play on Windows and Android?
Yes. AAC is widely supported across Windows, Android, Mac, and most music and media apps, which is a big part of why people convert away from the more niche M4B format.
Can I convert M4B to AAC without uploading it anywhere?
Yes. A desktop app like Morphjet converts the file on your own computer, so the audiobook never travels over the internet. You can do it with your wifi off.
Morphjet runs this conversion and 2,747 others, all on your machine. Available now.
One-time purchase, no subscription. 14 days to change your mind.