An M4A file is an MPEG-4 file that contains only audio. The name stands for MPEG-4 Audio, and the extension was popularised by Apple’s iTunes Store in the 2000s to tell audio-only files apart from MP4 videos. Today M4A is used by iPhone Voice Memos, GarageBand, iTunes purchases, many Android recorders and podcast apps.
What’s inside
The .m4a extension describes the container, not the codec. Most M4A files contain AAC (Advanced Audio Coding), a lossy codec designed as MP3’s successor, which sounds better than MP3 at the same bitrate. Some M4A files instead contain Apple Lossless (ALAC), which keeps every detail, like FLAC.
Related extensions
- .m4r: iPhone ringtones. The same AAC-in-MPEG-4 format, limited to 40 seconds.
- .m4b: audiobooks, which support chapters and remembering your place.
- .m4p: iTunes purchases protected with DRM before 2009. These can only be played in authorised apps.
What M4A is good at
- Quality for size. AAC at 128–256 kbps sounds as good as or better than MP3 at higher bitrates.
- Apple ecosystem. Native on iPhone, iPad and Mac.
- Metadata. Supports titles, artwork and chapters.
Where M4A falls short
- Compatibility. Some older car stereos, MP3 players, Windows tools and upload forms don’t accept M4A.
- Ambiguity. The same extension can mean lossy AAC or lossless ALAC, and some players support only one.
- Protection. Older iTunes purchases and Apple Music downloads are protected and can’t be converted.
M4A and other formats
Convert M4A to MP3 for maximum compatibility, or to WAV for editing and transcription. M4R ringtones can be made from an MP3 by encoding it as AAC and trimming it to 40 seconds.