M4A is an audio container format used by Apple — technically an MP4 container holding AAC audio, given a different extension so your OS knows it's audio, not video.
Safe format
Type Audio
By Apple / ISO
MIMEaudio/mp4
Drop any file to identify it
We read file headers, not extensions. Nothing gets uploaded.
M4A is an audio container format used by Apple — technically an MP4 container holding AAC audio, given a different extension so your OS knows it's audio, not video. Every voice memo you have ever recorded on an iPhone is an M4A file. iTunes purchases, Apple Music downloads, and GarageBand exports all use this format. Quality is better than MP3 at the same bitrate. Support is universal on Apple devices and very good everywhere else, though some older hardware and software still expects MP3.
Technical details
Full Name
MPEG-4 Audio
MIME Type
audio/mp4
Developer
Apple / ISO
Magic Bytes
00 00 00 ?? 66 74 79 70 4D 34 41
Safety
.m4a is a known, safe format.
What opens it
Apple Music / iTunes
FREEmacOS / iOS / Windows
VLC
FREEAll
Windows Media Player
FREEWindows
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FAQ
What's the difference between M4A and MP3?
M4A (AAC) sounds better at the same file size. MP3 has slightly broader legacy support. For modern use, both work everywhere that matters. Convert with <a href="https://fwip.app/tools/m4a-to-mp3/">fwip</a> if you need MP3.
Is M4A the same as AAC?
Almost. M4A is the container; AAC is the codec inside. It is like the difference between a box and its contents. Renaming .m4a to .aac does not work — the container format matters.
How do I convert M4A to MP3?
Use <a href="https://fwip.app/tools/m4a-to-mp3/">fwip's M4A to MP3 converter</a>. It runs entirely in your browser — no upload, no server processing, no account needed.