What is an M4R file?
M4R is the file type iPhone uses for ringtones. Inside, it's AAC audio, the same as an M4A file, just with a different extension so Finder and iTunes know it's a ringtone. That's why simply renaming an MP3 to .m4r doesn't work: the audio has to be converted to AAC.
FoneVibe converts and trims in your browser, so your file never leaves your computer.
How to convert MP3 to M4R
- Tap Choose audio and pick your MP3. WAV, M4A, AAC, OGG, FLAC and video files work too.
- Trim the part you want. M4R ringtones can be up to 40 seconds.
- Keep the Computer tab selected, name your ringtone and click Download. The first M4R takes a little longer because the converter downloads once.
- Connect your iPhone, open Finder (Mac) or the Apple Devices app or iTunes (Windows), and drag the .m4r file onto your iPhone.
- On your iPhone, open Settings → Sounds & Haptics → Ringtone and pick it from the top of the list.
No computer? Skip the M4R
On iOS 26 or later you can set a ringtone directly on your iPhone. Choose the iPhone tab instead to download an M4A (up to 29 seconds) and follow the iPhone ringtone guide.
Questions
Can I rename .mp3 to .m4r?
No. An M4R must contain AAC audio. Renaming leaves MP3 audio inside, which iPhone won't accept as a ringtone.
Why is the limit 40 seconds?
Ringtones synced from a computer can be longer than ones added on the phone, but iPhone still rejects long files. 40 seconds is the safe maximum.
Is the converter safe?
Your file is converted inside your browser. It's never uploaded, so nobody else can see or keep it.