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How to convert M4A to MP3 on a Mac

· 6 min read

The Music app can convert M4A to MP3 with no extra software: set the import encoder to MP3 in its settings, add the file to your library, then choose File, Convert, Create MP3 Version. If you would rather not route files through a music library, ffmpeg in Terminal or Manatee will convert a folder of M4As in one go. The one file neither can help with is an old protected iTunes purchase (.m4p), which stays locked to the account that bought it.

What an M4A actually is

M4A is a container, not a codec. It is an MPEG-4 file that holds audio only, and on a Mac that audio is almost always one of two things:

  • AAC, lossy, the format of iTunes Store purchases, Voice Memos, and most rips made in the Music app.
  • Apple Lossless (ALAC), lossless, which you will see on files ripped with the “Apple Lossless Encoder” setting or downloaded from a lossless store.

Why does this matter? Because converting AAC to MP3 is a lossy-to-lossy conversion. Each lossy encoder discards a different set of details, so the MP3 will be a touch worse than the M4A it came from. It is usually fine, but it is a reason to use a generous bitrate and a reason not to round-trip files repeatedly. Converting ALAC to MP3, by contrast, starts from a perfect source. The background is in lossless vs lossy: what happens to audio when you convert it.

To see which one you have, open the file in the Music app, select it, press Command-I, and look at the File tab. Or select it in Finder, press Command-I, and check the Codecs line under More Info.

Option 1: the Music app, no install

This is the route Apple built in. It has one quirk: the converter only works on tracks that are in the library, so you add the file first.

  1. Open Music. Choose Music, then Settings (Preferences on older versions), then the Files tab.
  2. Click Import Settings. Set Import Using to MP3 Encoder. For Setting, choose Higher Quality (192 kbps), or pick Custom and select 320 kbps for the best result. Click OK, then OK again.
  3. Add the M4A to the library by dragging it into the Music window, or with File, then Import.
  4. Select the track in the library. Choose File, then Convert, then Create MP3 Version.
  5. A second copy of the track appears next to the first. Right-click the new one and choose Show in Finder to get the MP3 file.

The new MP3 lives inside the Music media folder. Copy or move it wherever you need it. If you do not want the original M4A in your library, select it and press Delete; Music will ask whether to keep the file on disk.

Music can convert many tracks at once: select them all before choosing Create MP3 Version. It cannot convert protected purchases, and it will skip them silently.

Option 2: ffmpeg in Terminal

If you already use Terminal, ffmpeg converts without touching any library. Install it with Homebrew (brew install ffmpeg), then:

  1. Open Terminal. Type cd with a trailing space, drag the folder of M4A files onto the window, press Return.
  2. For one file at 256 kbps:
ffmpeg -i "memo.m4a" -codec:a libmp3lame -b:a 256k "memo.mp3"
  1. For every M4A in the folder:
for f in *.m4a; do ffmpeg -i "$f" -codec:a libmp3lame -b:a 256k "${f%.m4a}.mp3"; done

The tags (title, artist, album, artwork) come across automatically. For Voice Memos, which are mono speech, -b:a 96k keeps the files compact with no audible loss.

Option 3: Manatee, for a folder in one drop

Manatee is the option for people who want the folder-of-files convenience without the command line.

  1. Open Manatee and choose Convert.
  2. Drop the M4A files (or the whole folder) into the window, or drag them onto the menu bar icon.
  3. Pick MP3 as the target.
  4. Each file shows as a job with progress. The MP3s are written alongside the originals; nothing is modified or deleted.

Manatee bundles ffmpeg inside the download, so the output is the same as the command line route, with no library import step and no upload to a website. It is free for 24 hours with every feature and then $9 once.

What it will not do: it does not remove copy protection from .m4p purchases, and it does not trim or edit audio. For editing, use an audio editor first and convert afterward.

Which bitrate to pick

Because M4A to MP3 is usually a lossy-to-lossy step, err on the high side:

  • Music: 256 kbps at minimum, 320 kbps if space is no concern. Encoding a 256 kbps AAC into a 128 kbps MP3 is where people notice a difference.
  • Voice Memos and lectures: 96 to 128 kbps is plenty. Speech does not benefit from more.
  • ALAC sources: treat these like FLAC and use 320 kbps or high VBR, since the source is perfect.

There is no way to get a better MP3 by choosing a bitrate higher than the source’s. A 128 kbps AAC encoded to 320 kbps MP3 is a larger file with the same flaws.

The protected purchase problem

Music bought from the iTunes Store before 2009 often arrived as .m4p files with FairPlay protection. Neither the Music app, ffmpeg, nor Manatee will convert them, and Manatee does not attempt to crack protection of any kind.

Apple’s own answer is iTunes Match or an Apple Music subscription, which upgrades eligible purchases to unprotected 256 kbps AAC. If that is not an option, burning the track to an audio CD and re-importing it works but is lossy and slow. Check the file extension before spending time on this: a plain .m4a is not protected.

Questions

My M4A plays in Music but the MP3 is silent or short. The source may be damaged in a way the Music app tolerates but the encoder does not. Try ffmpeg -i memo.m4a -c copy remuxed.m4a first, which rewrites the container without touching the audio, then convert the remuxed copy. Corrupted MP3 or M4A won’t play on Mac: how to repair it goes deeper.

Can I convert an audiobook M4B the same way? Yes, the container is identical, but chapters do not survive in MP3, so a long book becomes one long track. How to convert an audiobook M4B to MP3 on a Mac covers splitting by chapter first.

Does converting remove the metadata? No, and that includes things like the encoder name and any comments. If you are sharing the file, how to remove metadata from audio files on a Mac shows what is in there and how to strip it.

Why is the MP3 bigger than the M4A? AAC is more efficient than MP3, so at equal quality the MP3 is larger. If you chose 320 kbps and the source was 128 kbps AAC, the MP3 can be more than double the size with no improvement in sound. Match the bitrate to the source.