Convert MP3 to M4R, Free
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How to convert MP3 to M4R
M4R is the file format Apple uses for iPhone ringtones. It is technically identical to an M4A audio file, but with a different file extension that iTunes and the Finder recognize as a ringtone instead of a music file. To set a custom ringtone on an iPhone, you need a file under 40 seconds long with an .m4r extension, synced through Apple's system. Converting an MP3 clip to M4R is the standard way to create custom ringtones from your own audio.
This converter processes the conversion in your browser using WebAssembly. The MP3 is decoded and re-encoded as AAC audio inside an MPEG-4 container, then saved with the .m4r extension. No audio is uploaded to a server. The output file is ready to add to iTunes or Finder for syncing to your iPhone.
Prepare a short clip
iPhones accept ringtones up to 40 seconds long. If your MP3 is a full song, trim it to the section you want before uploading, using an audio editor or the trim option in this converter if available.
Upload the MP3
Drop the .mp3 file onto the converter. The converter accepts any standard MP3 file including mono and stereo files at any common bitrate.
Convert in browser
The WebAssembly engine transcodes the audio from MP3 to AAC and wraps it in an MPEG-4 container with the .m4r extension. Processing is fast for short clips.
Add to iPhone via iTunes
Download the .m4r file. Drag it into the Tones section in iTunes (or Finder on macOS Catalina and later) and sync to your iPhone. It will appear in Settings > Sounds > Ringtone.
Frequently asked questions
Why is there a 40-second limit for iPhone ringtones?
Apple set this limit as part of the M4R specification for iPhone ringtones. There is no technical reason an audio file cannot be longer; it is a platform design choice. Files longer than 40 seconds will be rejected during sync.
Can I set an M4R as an alert tone or only a ringtone?
Custom M4R files can be used for ringtones, text tones, and other alert sounds. In iPhone settings, the same file appears in both the Ringtone and Text Tone sections after syncing.
Is the audio uploaded to a server?
No. The entire conversion runs inside your browser via WebAssembly. Your audio never leaves your device.
The M4R file shows up in iTunes but my iPhone does not show it after sync. Why?
Confirm the file is in the Tones section (not the Music section) in iTunes. If syncing does not work over USB, try again with iCloud sync disabled. Some iOS versions require the file to be under 30 seconds despite the 40-second limit applying in principle.
Is M4R just M4A renamed?
Yes, essentially. M4R and M4A both contain AAC audio in an MPEG-4 container. The only difference is the file extension, which tells Apple software to treat it as a ringtone rather than a music file.