Convert M4A to MP3 in your browser

For the software that will not open an M4A. Worth knowing before you start: AAC is the better codec, so this is a compatibility win rather than a quality one.

M4A

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M4A to MP3 options

Bitrate (kbps) 192

Your M4A is already lossy, so this is a second pass and the two rounds of damage compound. 192 is the safe default for that reason even though the source may be 128: matching the source bitrate in a weaker codec loses more than it saves. Drop to 96 or below only for speech.

Downmix to mono Off

One channel instead of two, so roughly half the size again. A voice memo is almost always effectively mono already, so this is usually free on one.

Strip tags and cover art Off

Off by default. An M4A from Apple Music carries the artist, album and cover art, and they are written into the MP3 as ID3 tags unless you turn this on.

Convert to a target size Off

MP3 size is bitrate times duration, so we work the bitrate out from the length of your recording. If your figure needs less than 32 kbps we say so rather than pretending.

How to convert M4A to MP3

01

Drop the M4A files

Voice memos, Apple Music exports, Zoom or Teams recordings. Nothing is uploaded, which matters more than usual for a recording of a meeting.

02

Pick a bitrate

192 keeps the second lossy pass honest. For speech, turn on mono and drop to 96 or 64.

03

Save the MP3

A .mp3 that transcription services, older car stereos, podcast hosts and Windows Media Player all accept without argument.

Is M4A or MP3 better, and why convert?

M4A is better. It is a container holding AAC, the codec designed as MP3's successor, and at any given bitrate it sounds closer to the original. An M4A at 128 kbps is roughly comparable to an MP3 at 192. Nothing about this page changes that: converting an M4A to MP3 makes the audio worse, not better.

People convert anyway, and they are usually right to. MP3 is the format that plays everywhere without a conversation: older car head units, gym equipment, DAW imports, transcription services, podcast hosts, church PA systems, Windows machines that have never had a codec pack installed. A file that plays is worth more than a file that sounds marginally better and does not.

What matters is the setting. Because your M4A has already been through a lossy encoder, this is a second pass, and the two rounds of discarding compound: the MP3 encoder is making judgements about audio that has already had detail removed, and it cannot tell what was taken. That is why this page defaults to 192 rather than matching whatever your source happens to be. Encoding a 128 kbps AAC as a 128 kbps MP3 loses noticeably more than the numbers suggest.

M4A to MP3 FAQ

Why does the MP3 come out bigger than my M4A?

Because MP3 needs more bits to sound the same. If your M4A was 128 kbps and this page encodes at 192, the file grows by half, and that is the trade being made: the extra bytes are what stops the second lossy pass from being audible. If size matters more than fidelity, pick 128 and accept a little more damage.

Will it sound worse?

Slightly, and unavoidably. Two lossy encodes in a row always lose more than one. At 192 kbps from a normal M4A the difference is very hard to hear on ordinary equipment. At 128 from a 128 source it starts to show on cymbals and sibilance.

Is this the same as an iPhone voice memo?

Yes. Voice Memos records to M4A, and the file it shares is what this page takes. For speech, turn on mono and drop the bitrate to 64 or 96: it will sound the same and be a fraction of the size.

Is my recording uploaded anywhere?

No, and this is the page where that matters most. Meeting recordings, interviews and voice memos are exactly the files people should not be handing to an unknown server. The decode and the encode both run in this tab.

What about M4B, M4R or AAC files?

M4B (audiobooks) and M4R (ringtones) are the same container with a different extension, and a plain .aac file is the raw stream. Rename to .m4a and they will convert here. Chapter marks in an M4B are not carried across, because MP3 has no equivalent.

Do the artist and album survive?

Yes, unless you turn on "Strip tags and cover art", which is off by default here. Tags are rewritten as ID3 in the MP3 so your music library still recognises the file.

Are my M4A files uploaded to convert them?

No. The M4A is decoded and the MP3 is written by your own browser, in this tab. There is no upload endpoint in the site for a file to go to, which you can check in your network tools: convert something and watch that no request carries it. Disconnect from the network after the page loads and it still works.