CAF to M4R Ringtone Converter

Convert CAF to M4R: Make an iPhone Ringtone from a Core Audio File

CAF, Apple's Core Audio Format, is the file you meet when you work with sound on a Mac: alert sounds in an Xcode project, effects bounced out of a sound-design session, recordings made by iOS apps through Apple's audio frameworks, and many of the Apple Loops installed with GarageBand and Logic Pro. It is a perfectly good audio file, but the iPhone will not list it as a ringtone. Custom tones have to arrive as M4R: AAC audio in an MPEG-4 container with the .m4r extension. This page converts the CAF to that format and trims it to ringtone length in the same pass.

How to Convert CAF to M4R

1. Upload Your CAF File: Drag the .caf onto the page or click "+ Add Files". Batch upload is supported, so a folder of app sounds can be converted with one set of options.
2. Choose a Bitrate under File Compression: AAC is the only codec for M4R. Pick Constant Bitrate (8-384 kbps) for a predictable size, Variable Bitrate (five AAC bands, from 20k-32k up to 96k-112k) for the best quality per byte, or type a Custom Bitrate. Quality Preset leaves the exact rate to the encoder.
3. Trim to 30 Seconds or Less: Under Trim, enter a Start time and a Duration, in seconds or HH:MM:SS.sss. Apple says iPhone ringtones can be up to 30 seconds long, and the note under Duration says the same. Leave Audio Channel and Audio Sample Rate on Original unless you have a reason to change them.
4. Convert and Download: Click Convert and save the .m4r. Files travel over TLS, are processed on our servers and are deleted automatically after a few hours. Free, no sign-up, no watermark.

Why Renaming a .caf to .m4r Does Not Work

CAF is a container, not a codec, and it is a different container from the one the iPhone expects. Inside a CAF you will commonly find linear PCM, Apple Lossless (ALAC), AAC, IMA4 ADPCM or µ-law/A-law audio, wrapped in Apple's own chunk structure with 64-bit sizes, which is why long recordings use it: there is no 4 GB ceiling. An M4R is an MPEG-4 file. Renaming the extension changes the label but leaves the CAF structure underneath, so the file still is not a tone.

Conversion decodes whatever the CAF holds and writes a fresh AAC-LC stream into an MPEG-4 file. We use the same MPEG-4 muxer for M4R as for M4A, and a tool such as ffprobe reports the result as AAC LC with the major brand M4A . In other words an M4R and an M4A are the same kind of file; the .m4r extension is what tells Finder, iTunes and the iPhone that this one is a ringtone. If you want the CAF as ordinary music instead, use CAF to M4A.

CAF vs M4R at a Glance

What's Inside Your CAF, and What to Pick

On a Mac, run afinfo yourfile.caf in Terminal; the "Data format" line names the codec. Then use this as a starting point:

A ringtone is short, so file size barely matters. AAC bitrate in kbps multiplied by seconds and divided by 8 gives kilobytes: 30 seconds at 128 kbps is about 480 KB, and at 256 kbps about 960 KB. Spend the bits; the phone will not notice.

Getting the Tone onto Your iPhone

There are three usual routes. On a Mac with macOS Catalina or later, connect the iPhone, select it in the Finder sidebar and drag the .m4r onto it. On Windows, add the tone with iTunes. On the iPhone alone, save the file to Files, import it into GarageBand and use Share > Ringtone, which is the route Apple documents; GarageBand exports ringtones of up to 30 seconds.

Once it is on the phone, open Settings > Sounds & Haptics > Ringtone and pick it. To give the sound to one person only, open Contacts, choose the person, tap Edit and set Ringtone or Text Tone. Short app chimes often work better as text tones than as ringtones.

Frequently Asked Questions

Can I rename a .caf file to .m4r instead of converting it?

No. The CAF and MPEG-4 containers are structured differently, so a renamed CAF is still a CAF and will not be accepted as a tone. Even a CAF that already holds AAC needs to be rewritten into an MPEG-4 file. Converting takes seconds for a clip this short.

How long can an iPhone ringtone be?

Apple's support article on custom ringtones says ringtones can be up to 30 seconds long, and GarageBand shortens a longer ringtone automatically when it exports one. A 40-second figure is widely quoted from the iTunes era, but it is not in Apple's current documentation, so aim for 30 seconds or less with the Trim control.

My CAF is a one-second alert sound. Will that work?

Yes. The converter has no minimum length, and a short chime makes a natural text tone. Leave Trim on Unchanged, convert, and assign it under Settings > Sounds & Haptics or per contact. Apple's GarageBand guide also notes that an exported ringtone can be used as a Standard Text Tone.

Should the ringtone be mono or stereo?

Keep Audio Channel on Original. Many app sounds are mono already, and turning mono into stereo only duplicates the same signal. If the CAF is a stereo music loop, Original keeps its stereo image.

Will loop points, markers or channel layouts carry over?

No. CAF can store markers, regions and channel-layout information that has no counterpart in an M4R, so only the audio is carried across. That also means an Apple Loop's loop points are not kept; the tone plays the audio you trimmed, as it is.

Do I need M4R for an Android phone?

No. Android does not use M4R; its ringtones are usually MP3 or OGG files. Convert with CAF to MP3 instead and set the result from the phone's sound settings.

I already have an M4R that is too long. Can I shorten it?

Yes. Use Trim M4R to pick a start and end on the waveform without converting from the CAF again. For other source formats, the M4R converter lists every route into M4R.

What happens to my CAF after conversion?

It is uploaded over an encrypted (TLS) connection, converted on our servers and deleted automatically after a few hours. Nothing is shared or made public, and no account is needed.