Why renaming is not enough
M4R is Apple's ringtone format: AAC audio in an MP4 container, with the .m4r extension. Since a raw .aac file already contains AAC audio, it is tempting to simply rename it. That does not work, because raw AAC has no MP4 container, and the iPhone checks for one. The converter builds a proper M4R file around the audio so that Finder, iTunes and the iPhone accept it.
Prepare the clip first
Ringtones on iPhone are limited to 40 seconds, and text or alert tones to 30 seconds. Raw AAC recordings are often longer, for example a captured song from the radio or a sound taken from a video. Before converting:
- Open the file in Cut audio and select the part you want, no longer than 40 seconds.
- Add a short fade-in and fade-out so the ringtone does not start with a click.
- Export the clip and convert it to M4R here.
The iPhone ringtone maker combines these steps and enforces the 40-second limit. This page can also cut a 40-second part for you, with a short fade-out: set the start time under Cut to 40 seconds.
Quality and size
The audio is re-encoded to AAC inside the M4R. Choose a bitrate at least as high as the source to avoid audible loss. A phone speaker cannot show the difference between 192 and 256 kbps, so 192 kbps is a good choice for music and 128 kbps for voice or simple sounds.
| Length | M4R at 128 kbps | M4R at 192 kbps |
|---|---|---|
| 10 seconds | about 160 KB | about 240 KB |
| 30 seconds | about 480 KB | about 720 KB |
| 40 seconds | about 640 KB | about 960 KB |
Installing on the iPhone
Connect the phone to a Mac, select it in Finder and drag the M4R into the window. On Windows, use iTunes and drop the file on the Tones section of the device. Without a computer, save the file to Files, open it in GarageBand for iOS and export it as a ringtone. Then pick it under Settings, Sounds and Haptics. The name shown on the phone is the file name, so rename it before transfer.