What is an M4A file?
M4A is an MP4 file that contains only audio, usually AAC, the format Apple adopted for iTunes in 2003 and still uses across iPhone, iPad and Mac. The extension tells you it's audio-only; inside, it's the same container as an MP4 video. Less commonly, an M4A holds ALAC, Apple's lossless codec.
AAC is a better codec than MP3, giving slightly better sound at the same size, so there's nothing wrong with M4A itself. The issue is compatibility: some car stereos, older MP3 players, DJ software, website upload forms and voice-message systems only accept MP3.
Where do M4A files come from?
M4A turns up in more places than most people realise:
- iPhone Voice Memos: every recording is saved as M4A.
- Music bought from the iTunes Store (DRM-free since 2009) and songs ripped with iTunes or the Music app.
- GarageBand exports and iPhone ringtones (which are M4A files renamed to .m4r).
- Many Android recorders and call recorders, and audio exported from video editors.
How do I get a voice memo off my iPhone?
In Voice Memos, tap the recording, tap the ••• menu, choose Share and then Save to Files. Then open this page in Safari, tap Choose a file and pick it from Files. After converting, the MP3 is saved to Files → Downloads, ready to email, upload or send.
On a Mac, voice memos are in the Voice Memos app; drag one to the desktop to get the M4A file.
Quality and what can't be converted
The audio is decoded and encoded as a 192 kbps MP3. Converting AAC to MP3 is a lossy-to-lossy step, so in theory a little detail is lost; at 192 kbps it's very hard to hear, especially for speech. Lossless ALAC files convert just as well and come out the same size as any other 192 kbps MP3.
Songs downloaded for offline listening in Apple Music are protected with DRM and can't be read by any converter. The same applies to old iTunes purchases from before 2009 (.m4p files).
Private conversion
Voice memos are often personal: meetings, interviews, lectures, medical appointments. This converter runs in your browser with ffmpeg, so the recording is never uploaded and no copy exists anywhere but your device.
Can I convert WhatsApp voice notes to MP3?
Yes, with the Audio Converter rather than this page. WhatsApp voice notes aren't M4A: they're Opus audio, saved with an .opus or .ogg extension, and Telegram voice messages are Opus too. The Audio Converter accepts any audio format ffmpeg can read, so it turns them into MP3 just as easily.
Samsung's Voice Recorder and many other Android recorder apps save M4A, so their recordings work here directly.
Long recordings
Voice memos of meetings and lectures can run for hours. A one-hour M4A memo converts in well under a minute on a laptop and a few minutes on a phone, and the MP3 comes out around 85 MB at 192 kbps. Before converting a long memo for a transcription service, check whether it accepts M4A: most do, and then the original file is both smaller and one conversion closer to the source.