CAF file (Core Audio Format)
Core Audio Format, an Apple container with no size limit.
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Convert CAF to MP3, free and without uploading it.
What is a CAF file?
In short: A CAF file (.caf) is an audio file in the CAF format. CAF was designed to remove the 4 GB ceiling that WAV and AIFF inherited from their 32-bit headers, so it can hold recordings of essentially unlimited length. It can be converted to MP3, WAV or FLAC for free in a web browser with iHateFiles, without uploading it.
Apple's Core Audio Format, introduced with macOS 10.4 in 2005.
CAF was designed to remove the 4 GB ceiling that WAV and AIFF inherited from their 32-bit headers, so it can hold recordings of essentially unlimited length. It carries almost any codec and detailed per-channel metadata.
What CAF is good at
- No practical size limit
- Holds any codec, compressed or not
- Rich channel and marker metadata
Where CAF falls short
- Apple-centric
- Not supported by browsers
- Less portable than WAV for interchange
When to use CAF
Convert CAF to WAV or M4A to move a recording off a Mac.
How to open a CAF file
macOS, Logic, and VLC.
| Windows | VLC. CAF is an Apple container and almost nothing on Windows reads it. |
|---|---|
| macOS | Opens natively in QuickTime and Music. |
| Linux | VLC or FFmpeg-based players. |
| Phone | Native on iOS. |
| In a browser | No browser plays CAF. |
The thing that usually goes wrong
A CAF can contain compressed audio, so converting one to WAV does not necessarily make it lossless: that depends on what was inside.
Inside a CAF file
Core Audio Format was introduced by Apple in 2005 to get past a limit that had become genuinely awkward: WAV and AIFF both store sizes in 32-bit fields, which caps a file at 4 GB. At 24-bit 96 kHz stereo that is about two hours, and a live recording rig can exceed it in an afternoon.
CAF uses 64-bit offsets, so the practical limit is gone. It also decouples the container from the codec entirely — a CAF can hold uncompressed PCM, ALAC, AAC or IMA ADPCM — and carries markers, regions and channel layout descriptions that a plain WAV cannot.
The reason to convert one is simply reach: outside Apple software almost nothing opens CAF, so a file that is perfectly well-formed is functionally unreadable to whoever you send it to.
| Full name | Core Audio Format |
|---|---|
| Magic bytes | 'caff' (63 61 66 66) |
| Introduced | Apple, 2005 |
| Size limit | None in practice — 64-bit offsets |
| Codecs it holds | PCM, ALAC, AAC, IMA ADPCM and others |
| Carries | Markers, regions, channel layouts |
Not sure the file really is a CAF? Identify it by its contents, whatever its extension says.
Questions
What is a CAF file?
CAF stands for Core Audio Format. Core Audio Format, an Apple container with no size limit. Files use the .caf extension.
What does CAF stand for?
CAF stands for Core Audio Format.
How do I open a CAF file?
On Windows: VLC. CAF is an Apple container and almost nothing on Windows reads it. On a Mac: Opens natively in QuickTime and Music. On a phone: Native on iOS. Or convert a CAF here to a format that opens everywhere, free and without uploading it.
Can I convert CAF for free?
Yes. Every conversion here is free and unlimited, because your own device does the work rather than a server we have to pay for.
Is CAF lossless?
It depends on what is inside. CAF is a container, and it can hold either a lossless codec or a lossy one; the extension alone does not say which.