Audio
M4A to MP3, for devices that never caught up
M4A is what iPhones, iTunes and most voice recorders produce. It sounds fine and plays badly on anything that is not Apple, which is why this conversion exists.
Files are processed on your device · nothing is uploaded, stored or logged
How it works
Pick your file. The browser reads it straight from disk. There is no upload progress bar, because there is no upload.
The encoder loads once. A WebAssembly build of FFmpeg, around 30 MB, downloads the first time you use the site and stays cached afterwards.
Your processor does the work. Everything happens in this tab, at roughly half of real time on a modern laptop.
Save the result. The finished file is assembled in memory and handed to your downloads folder.
Where M4A files come from
Voice Memos on an iPhone saves M4A. So does iTunes, so do most Android voice recorders, and so does any video whose audio has been pulled out without re-encoding.
The format itself is technically better than MP3 — it uses AAC, which sounds cleaner at the same bitrate. The problem is support. Car stereos, older MP3 players, dictation software, transcription services and plenty of upload forms still expect MP3 and nothing else.
Converting costs a small amount of quality because the audio is decoded and re-compressed. At 192 kbps and above that loss sits below what people can hear in ordinary listening.
A faster option worth knowing
If your M4A came out of a video and you only need it to play somewhere, check whether the destination accepts M4A first. Skipping the conversion entirely keeps the audio bit-for-bit identical, and more players support it every year.
Common questions
Is M4A the same as AAC?
Nearly. M4A is the container; AAC is almost always the audio inside it.
Will my voice memo lose quality?
Slightly, but speech recordings are very forgiving. At 128 kbps a voice memo is indistinguishable from the original.
Why does my car stereo reject M4A?
Most car head units only implement MP3 and WMA. It is a licensing decision rather than a technical limit.
Do my files get uploaded?
No. Everything happens in your browser.