Convert M4A to MP3

Convert M4A voice memos and iTunes audio to MP3 in your browser. Free and private, with no upload, no size limit and no watermark.

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AAC audio inside an MP4 box, which is all an M4A is

There is no such thing as M4A the codec. An .m4a file is an MPEG-4 container, the same box structure that holds video in an .mp4, with the video boxes simply absent. What lives inside is normally AAC, the codec MPEG standardised as the successor to MP3 and Apple adopted wholesale in 2003 when the iTunes Store opened.

Apple then made it the default everywhere: iTunes and the Music app rip CDs to it, Voice Memos records to it on iPhone, iPad and Mac, GarageBand bounces to it, and Apple Music uses the same codec for its own protected downloads. That is why an .m4a in your files is almost always either a ripped album track or somebody speaking.

AAC is a genuinely better codec than MP3 at the same bitrate. It uses longer transform windows, better stereo joint coding and no legacy patents to route around, and at 128 kbps it comfortably beats a 128 kbps MP3. None of which helps when the target device has never heard of it. That is the whole reason this page exists: not to improve the audio, but to put it in the one format nothing refuses.

The same extension can hold Apple Lossless

Here is the trap that catches people converting a music library. Apple Lossless, ALAC, also lives in a .m4a file. Two tracks in the same folder with the same extension can be a 128 kbps lossy rip and a bit-perfect lossless copy, and nothing in the filename tells you which.

FFmpeg decodes both without being told, so the conversion works either way and you never have to pick. What changes is your bitrate choice. Coming from a lossy AAC there is little point pushing to 320 kbps, because the detail that was thrown away in 2005 does not come back. Coming from ALAC you are making the same decision a FLAC to MP3 conversion involves, and 320 kbps is worth the bytes.

The .aac branch and why the demuxer needs telling

This page also accepts a bare .aac file, and the module treats it differently from an .m4a on purpose. A raw .aac is an ADTS stream: AAC frames laid end to end with small sync headers and no container around them at all. It is what broadcast encoders and some ripping tools emit, and it is not the same thing as AAC packaged in MPEG-4 boxes.

FFmpeg picks its demuxer partly from the filename, so the code checks the extension and hands the file over as input.aac or input.m4a accordingly. Handing an ADTS stream to the MP4 parser would simply fail. It is a one-line branch and it is the reason both extensions can share one page instead of needing two.

Album art vanishes, and that is deliberate

iTunes embeds cover art in the container, and FFmpeg surfaces that artwork as a video stream rather than as metadata. Left alone, the encoder would faithfully carry that stream into the output, and a file that is nominally an MP3 with a video track in it trips up car head units, older phones and a fair number of desktop players.

So the converter passes -vn, which disables video output and so leaves that artwork stream behind before encoding. You get plain audio out. If the artwork matters, add it back with a tag editor once the MP3 exists, which is also when you would fix a title or an album name.

Handing an M4A to the converter

  1. Drop your .m4a or .aac file onto the box above, or click Choose a file to browse for it.
  2. Choose an Audio quality. 192 kbps (recommended) suits voice memos and most rips; take 320 kbps (highest quality) when the source is Apple Lossless or a finished mix.
  3. Click Convert M4A to MP3. A progress bar and a Cancel button take the place of the button while FFmpeg works.
  4. Download the MP3. It carries your original filename with the extension swapped for .mp3.

Transcoding one lossy codec into another

Be clear-eyed about what this step is. Unless the source was ALAC, you are decoding audio that has already been through one lossy encoder and feeding the result into a second one. The second encoder cannot see what the first removed, so it makes its own decisions about what to discard on top.

In practice, for a voice memo, a lecture or a podcast this is entirely inaudible. For dense music at a low target bitrate it is the case where a careful listener hears the difference, which is the argument for 320 kbps when a track matters and for keeping the M4A rather than deleting it. The wider comparison of what each format costs you is covered in the audio converter and editing tools guide.

Voice Memos, .m4p purchases and the files this page refuses

The everyday jobs are unglamorous and all the same shape: a meeting recording that a transcription service will not accept, a voice memo that needs to become an email attachment, a CD rip that a car stereo built in 2011 silently skips, a GarageBand bounce for a collaborator on Windows.

The one file it will not help with is an old .m4p. Those are FairPlay-protected iTunes Store purchases from before 2009, and the extension is not in the accepted list, so the dropzone rejects them outright rather than pretending. If you want the reverse direction for an iPhone ringtone, MP3 to M4R re-encodes an MP3 to AAC inside the MP4 variant iOS expects, cut to the 30 seconds Apple allows a ringtone, and WAV to MP3 covers the uncompressed case.

Frequently asked questions

My iTunes file ends in .m4p and the page will not take it. Why?

An .m4p is a FairPlay-protected purchase from the old iTunes Store, and the protection is part of the file rather than a wrapper around it. The extension is not in this page's accepted list, so you get an "Unsupported file type" message instead of a failed conversion, which is the honest outcome, because FFmpeg cannot decrypt it either.

How do I tell whether my .m4a is AAC or Apple Lossless?

You often cannot from the outside, which is the awkward part of the extension. A rough guide is size, because ALAC tracks tend to run tens of megabytes for a normal song while an AAC rip of the same track is a few. Either decodes here without you choosing anything, but converting an ALAC file is a lossless-to-lossy step, so take 320 kbps for it.

Where did the album artwork go?

It was dropped on purpose. FFmpeg reports embedded cover art as a video stream, and this converter passes -vn so that only audio reaches the encoder. Without it the run can produce something that is technically an MP3 with a still image glued to it, which confuses several players. Re-add artwork afterwards in a tag editor if you need it.

Does an iPhone Voice Memo convert without any extra steps?

Yes, once the file is on the device you are browsing from. Voice Memos stores recordings as M4A, so sharing one to Files, to iCloud Drive or to yourself by email gives you an .m4a that this page takes directly. Nothing has to be renamed or unpacked first.

Will the MP3 be bigger or smaller than the M4A?

Usually bigger, and that surprises people. AAC at a given bitrate is more efficient than MP3, so an iTunes rip at 256 kbps re-encoded to a 320 kbps MP3 gains size while losing a little detail. Choosing 192 kbps normally lands you near or under the original, which is a reasonable trade when portability is the goal.

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