Format comparison
AAC vs M4A
How do AAC and M4Acompare? Here's everything you need to know to choose the right format — and how to convert between them.
.aac
Full guide →Advanced Audio Coding
AAC is the successor to MP3, offering better sound quality at lower bitrates. It's the default audio format for Apple Music, YouTube, and most streaming platforms.
.m4a
Full guide →MPEG-4 Audio
M4A is an audio-only MPEG-4 container, typically containing AAC or ALAC encoded audio. It's Apple's preferred format for music files in iTunes and Apple Music.
| Specification | AAC | M4A |
|---|---|---|
| Full name | Advanced Audio Coding | MPEG-4 Audio |
| Extension | .aac | .m4a |
| MIME type | audio/aac | audio/mp4 |
| Category | Audio | Audio |
| Developer | ISO / Fraunhofer / Dolby / Sony / Nokia | Apple / ISO |
| Year introduced | 1997 | 2001 |
| Compression | Lossy | Lossy |
AAC advantages
- Better quality than MP3 at same bitrate
- Default format for iTunes and Apple Music
- Widely used in streaming
- Supports up to 48 channels
AAC limitations
- Patent-encumbered
- Slightly less universal than MP3
- Encoding quality varies by implementation
- DRM can restrict usage
M4A advantages
- Better quality than MP3 at same size
- Native Apple ecosystem support
- Supports both lossy (AAC) and lossless (ALAC)
- Rich metadata and artwork
M4A limitations
- Less universal than MP3
- Confusing relationship with AAC
- Some older devices don't support it
- Apple-centric ecosystem
Which should you use?
Both are excellent audio formats. AAC is preferred for apple music and itunes, while M4A shines at itunes music library.
Best uses for AAC
Apple Music and iTunes
YouTube and streaming platforms
Mobile music playback
Digital broadcasting (DAB+)
Best uses for M4A
iTunes music library
Apple Music downloads
Podcast distribution
Audiobook files
Convert between AAC and M4A
Need to switch formats? Convert for free with SquishConvert.