Manatee

What a .caf file is, and how to convert it to MP3 on a Mac

· 6 min read

A .caf file is an audio file in Apple’s Core Audio Format. Macs and iPhones play most of them without complaint, which is why they go unnoticed until you send one to someone on another platform, upload it to a website, or drop it into an app that only knows MP3 and WAV. The fix is to convert it. On a Mac you can do that with built-in tools if you accept a short detour, or in one step with a converter that reads CAF directly.

Where .caf files come from

CAF is a container Apple designed for its own audio software, as a more flexible alternative to AIFF and WAV. You tend to meet it in a handful of places:

  • Audio messages saved from Messages. Voice messages kept or dragged out of a conversation often arrive as .caf files.
  • GarageBand and Logic loops. Apple Loops are commonly stored as .caf.
  • Sound effects and recordings from apps, particularly apps built with Apple’s developer tools, where CAF is the default for many audio tasks.
  • Some voice and field recording apps that export in Apple’s native format.

Apple uses it because a CAF file can hold almost any audio encoding, from uncompressed PCM to AAC to Apple Lossless, and it has no practical size limit, unlike WAV, which tops out at 4 GB. That flexibility is also the catch. “CAF” tells you the wrapper, not what is inside it, and software outside Apple’s world rarely recognizes the wrapper at all.

Check what is inside first

Two quick ways to see the encoding:

  1. Select the file in the Finder, press Command-I, and look under More Info. The codec is often listed there, for example AAC or Linear PCM.
  2. For a definite answer, open Terminal and run afinfo on the file:
afinfo ~/Desktop/recording.caf

The “Data format” line names the encoding: lpcm for uncompressed audio, aac for AAC, alac for Apple Lossless, and so on. The output also shows the sample rate and the duration.

This matters for quality. If the CAF holds uncompressed or lossless audio, converting to MP3 is a single lossy step and will sound fine at a reasonable bitrate. If it already holds AAC, converting to MP3 stacks one lossy format on top of another. That is usually fine for speech and worth knowing for music. Lossless vs lossy explains the trade in more detail.

The built-in route: afconvert, then Music

macOS includes a command-line converter called afconvert that reads CAF natively. It cannot write MP3, because the audio frameworks built into macOS include no MP3 encoder, but it can write WAV or M4A, and either may be all you need.

To WAV, uncompressed and accepted almost everywhere:

afconvert -f WAVE -d LEI16 ~/Desktop/recording.caf ~/Desktop/recording.wav

To M4A, compact and playable on nearly every current device:

afconvert -f m4af -d aac ~/Desktop/recording.caf ~/Desktop/recording.m4a

QuickTime Player gets you to M4A without Terminal: open the CAF, choose File > Export As > Audio Only, and save.

If you really do need MP3, the Music app can finish the job from the WAV:

  1. In Music, choose Music > Settings, click Files, then Import Settings.
  2. Set Import Using to MP3 Encoder, pick a quality, and click OK.
  3. Choose File > Import and add the WAV to your library.
  4. Select it, then choose File > Convert > Create MP3 Version.
  5. Right-click the new copy and choose Show in Finder.

This works, but it is fiddly for more than one or two files, and it leaves copies in your Music library that you will want to delete afterward.

Converting CAF to MP3 in one step with Manatee

Manatee takes CAF directly and writes MP3, M4A, WAV or FLAC, so there is no detour through another format and nothing lands in your music library.

  1. Drag the .caf file, or a whole selection of them, onto Manatee’s menu bar icon or into its window.
  2. Choose Convert, then MP3.
  3. The converted files appear next to the originals, which are left exactly as they were.

It handles batches, so a folder of loops or a stack of saved voice messages goes in at once, and it takes mixed piles too: CAF alongside AIFF, AMR, WMA or anything else among its 122 input types. Everything is processed on your Mac. Nothing is uploaded, which is worth something when the recordings are private conversations. Every feature is free for the first 24 hours, then it is $9 once.

For converting many files at once more generally, see how to convert a batch of files at once on a Mac.

MP3, M4A or WAV: which to pick

  • MP3 if the file is going somewhere you do not control: a website form, a Windows PC, an old car stereo, a colleague who says “just send an MP3”. It is the one audio format everything accepts.
  • M4A if the destination is modern. At the same file size it generally sounds as good as MP3 or better, and every current phone and computer plays it.
  • WAV if the audio is going into an editor, or you want to keep full quality from an uncompressed CAF. It is large, but nothing is lost.

If you are sending to someone on Windows, how to convert files so they open on a Windows PC covers the other formats that tend to trip people up.

Questions

Can I just rename .caf to .mp3? No. Renaming changes the label, not the contents. Some players will refuse the file, and others will try to play it and fail. The audio has to be converted.

Why does the CAF play on my Mac but not on my friend’s phone? Apple devices understand the CAF container natively. Many other platforms do not, even when the audio inside is a common encoding like AAC.

Will converting a voice message to MP3 make it sound worse? Voice messages are already compressed for speech, so a conversion at a normal MP3 bitrate will sound the same to almost anyone. It will not make the original sound any better, either.