Free online M4R to AAC converter

Apple iPhone ringtones use the .m4r extension, while some editors, players, and hardware devices require a standalone .aac stream. Converting the file can make its audio usable outside an Apple ringtone library, but it does not preserve iPhone ringtone registration.

What the M4R format is

M4R is an Apple ringtone filename extension based on the MPEG-4 container format. Most M4R files contain AAC audio, but the extension identifies the file's ringtone purpose and does not guarantee a specific codec.

iPhone owners encounter M4R files when creating or transferring custom ringtones through iTunes, Finder-based iPhone workflows, or GarageBand. An M4R can contain metadata and an MPEG-4 container around its audio stream. If that stream is already AAC, it may be extracted without another lossy encoding step; another source codec must be transcoded.

What the AAC format is

AAC (Advanced Audio Coding) is a lossy audio codec used in Apple devices, streaming services, video files, smartphones, and media players. A standalone AAC file normally uses the .aac extension and stores an elementary stream, commonly with ADTS headers.

AAC generally delivers better quality than MP3 at comparable bit rates and produces relatively small files, but it is not lossless. Standalone AAC playback is less consistent than MP3 playback; some applications accept AAC only inside an .m4a or .mp4 container.

How to convert an M4R file

Using 101convert.com:

1. Open 101convert.com and select its audio conversion tool.
2. Upload the unprotected .m4r file.
3. Choose AAC as the output format and start the conversion.
4. Download the resulting .aac file and test it in the target application.

This option requires no installed software and is free to use. Do not upload private recordings or copyrighted material unless you have permission to process it.

Using FFmpeg: Inspect the audio codec before choosing between copying and re-encoding:

ffprobe -v error -select_streams a:0 -show_entries stream=codec_name input.m4r

If the output reports aac, extract the existing AAC stream into an ADTS file without another lossy generation:

ffmpeg -i input.m4r -vn -c:a copy -f adts output.aac

If the source uses another codec, encode it as AAC:

ffmpeg -i input.m4r -vn -c:a aac -b:a 192k -f adts output.aac

Use 128k for a smaller file or about 192k for a general music setting. The -vn option excludes video, and -f adts creates the common standalone AAC form. Some AAC profiles cannot be copied into ADTS; if the copy command fails, re-encode or retain AAC in an .m4a container if the destination supports it.

Quality and compatibility limits

Re-encoding an M4R that already contains AAC causes another lossy compression step. Use stream copying when the source is compatible AAC and the destination accepts ADTS; otherwise, encode once at the bit rate required by the target software.

Renaming file.m4r to file.aac changes only the filename. It does not remove the MPEG-4 container, so software expecting an ADTS AAC stream may reject the renamed file. Renaming is useful only when the receiving program recognizes the underlying container despite the extension.

The conversion does not retain Apple-specific ringtone registration, synchronization settings, or guaranteed metadata behavior. DRM-protected or otherwise restricted Apple audio cannot be converted by changing the extension or using FFmpeg; use an unprotected file that you are authorized to process.