M4A to MP3 Converter

What is inside an M4A file

M4A is an MPEG-4 file with no video in it. The extension was Apple's way of telling iTunes that a file is music rather than a movie; inside is almost always AAC, the codec Apple uses for its downloads and its Voice Memos app. Occasionally an M4A holds ALAC, Apple Lossless, instead — same extension, completely different contents.

Either way, ffmpeg reads both, so the converter does not need you to know which you have. It matters only for quality: an ALAC M4A converts like a lossless file, an AAC one like a lossy file.

Why convert M4A to MP3?

M4A files usually arrive as one of three things: the Voice Memos app on an iPhone, iPad or Mac, which saves every recording as M4A; songs bought from the iTunes Store (DRM-free AAC at 256 kbps since 2009) or ripped with Apple Music or iTunes; or GarageBand and other Apple apps' default audio export.

Some Android phones, older car stereos, MP3 players and Windows apps either ignore M4A or fail to read its tags.

Upload forms, school portals and learning platforms that accept only MP3.

Sharing a voice memo with someone whose software does not recognise the extension.

What happens to the sound

An AAC M4A is lossy, so converting it to MP3 decodes one lossy format and encodes another. AAC at a given bitrate is generally more efficient than MP3, so to keep the same perceived quality use an MP3 bitrate somewhat higher than the source: for a 256 kbps iTunes track, 320 kbps; for a 128 kbps voice memo, 160 or 192 kbps.

If the M4A turns out to be Apple Lossless, this is a first-generation encode, and the result is as good as the bitrate allows — the same as starting from WAV.

About 1–2 MB per minute is typical for M4A. As MP3, multiply the minutes by 0.96 MB at 128 kbps, by 1.44 MB at 192 kbps or by 2.4 MB at 320 kbps; that is the whole calculation, because MP3 here is constant bitrate.

Settings that suit an M4A source

Voice Memos records AAC at modest bitrates — or Apple Lossless, if Audio Quality is set to Lossless in its settings — and a voice needs little: 96 or 128 kbps mono is all the MP3 needs.

For iTunes music at 256 kbps AAC, choose 320 kbps stereo and leave the sample rate as it is — 44.1 kHz is what those files already use.

Title, artist, album and similar iTunes tags are mapped to ID3 in the MP3. Embedded artwork is not copied.

Problems you may run into with M4A

The converter cannot read a song from the Apple Music app — Apple Music streaming downloads are protected with FairPlay DRM (often with an .m4p extension). No legitimate converter can open them; only DRM-free purchases and your own recordings convert.

Track numbers or album art went missing — text tags carry over, but the cover image is dropped. Re-add artwork in your music player after converting.

The file plays but shows a strange duration — a voice memo still being synced from iCloud can be incomplete. Wait for the download to finish on your device, then convert again.

Your M4A stays on your device

Most audio converters on the web work by upload: the M4A goes to a server, is converted there, and waits on that server for you to collect it.

This converter brings the conversion to the file instead. ffmpeg, compiled to WebAssembly, runs in the tab; the M4A is read locally and the MP3 is produced on your device.

What does cross the network is the engine: a 32 MB download on first use, cached for the session. Your audio is never part of any request — disconnect after the engine loads and the converter still works.