M4A vs MP3
| Property | M4A | MP3 |
|---|---|---|
| Full name | MPEG-4 Audio | MPEG-1 Audio Layer III |
| File extensions | .m4a | .mp3 |
| Created by | MPEG container, popularised by Apple (iTunes) | Fraunhofer IIS and MPEG |
| Introduced | 2003 | 1993 |
| Compression | Lossy AAC (or lossless ALAC) | Lossy |
| Codecs inside | AAC, usually 128–256 kbps; sometimes ALAC | MP3, usually 128–320 kbps |
| Typical size | About 1 MB per minute at 128 kbps | About 1 MB per minute at 128 kbps, 2.4 MB at 320 kbps |
| Opens on | iPhone, Mac, Android and Windows 10+; some car stereos, older players and upload forms want MP3 | Every phone, computer, car stereo, speaker and app |
| Best for | Voice memos, iTunes purchases and good sound at small sizes | Music and podcasts that must play anywhere |
Why convert M4A to MP3?
M4A is an MPEG-4 file holding AAC audio, the format of the iPhone Voice Memos app, iTunes downloads and many Android recorders. It sounds better than MP3 at the same size, but plenty of places still only take MP3: car stereos from before about 2012, cheap MP3 players and speakers, some podcast hosts, school and work portals, and call systems.
Because both formats are lossy, converting re-encodes the sound once. Match or exceed the original bitrate to avoid audible loss: voice memos are typically around 64 kbps mono AAC, so 96–128 kbps mono MP3 keeps them clear; iTunes music is 256 kbps AAC, so use 256 or 320 kbps MP3.
Files protected by DRM (old iTunes purchases from before 2009, labelled M4P, and Apple Music downloads) cannot be converted by any honest tool, including this one. To trim a long memo before sharing, use the Audio Trimmer.