MP3 to M4R Converter

M4R is the container format iPhones use for custom ringtones, built on the same MPEG-4 audio structure as M4A but with a file extension that iOS recognizes as a ringtone during sync. Converting MP3 to M4R means re-encoding MPEG audio into AAC, then wrapping the result in an MP4 container with the .m4r extension.

Upload an MP3 file and the tool begins with step one: validating the file extension and checking its duration. iPhones enforce a 30-second ringtone limit, so the converter flags files that exceed that length and warns you before encoding begins. Step two loads FFmpeg WebAssembly in the browser and prepares the source audio stream. Step three runs the transcode using the AAC encoder at 128 kbps, which matches the bitrate Apple uses internally — going higher doesn't add perceptible quality for a short ring clip. Step four packages the audio in an MP4 container, renames the output to .m4r, and provides a download link.

Practical tip: trim your MP3 to 20–25 seconds before converting. Fades at the start and end of a ringtone make the loop less jarring when a call comes in. All processing happens locally in your browser. Files are never uploaded to our servers.