Free online MP3 to AMR converter

Some older mobile phones, voicemail systems, MMS applications, and telecommunications tools accept speech only as AMR. Converting an MP3 recording to AMR makes it usable in those systems and reduces its file size, although it is not suitable for preserving music quality.

What the MP3 format is

MP3 is a lossy audio format designed to reduce file size while retaining acceptable playback quality. Music players, operating systems, audio editors, CD-ripping software, smartphones, and voice recorders commonly create or export .mp3 files. MP3 supports mono or stereo audio, many bitrates, and common sampling rates including 44.1 kHz and 48 kHz.

What the AMR format is

AMR, or Adaptive Multi-Rate, is a speech codec standardized for mobile telecommunications and 3GPP media. The usual .amr file contains AMR-NB, which stores mono narrowband speech at 8 kHz using selectable bitrates from 4.75 to 12.2 kbit/s. These low bitrates produce very small files for voice messages, voicemail, MMS, and older mobile applications.

AMR-NB is optimized for speech, not music. Music, background noise, and other complex audio usually sound muffled or distorted after encoding. AMR-WB is a separate wideband format for higher-quality speech; it uses a 16 kHz sampling rate and is commonly stored with the .awb extension. Confirm which format the destination device or application accepts before converting.

How to convert MP3 to AMR

Using 101convert.com

1. Open the MP3-to-AMR converter on 101convert.com.
2. Select the source .mp3 file from your device and start the conversion.
3. Download the resulting .amr file when processing finishes.

This option requires no software installation and is suitable for occasional, non-confidential files. Use a local converter for private recordings, repeated jobs, or precise encoding settings.

Using FFmpeg locally

Install an FFmpeg build with AMR-NB encoding support, then run:

ffmpeg -i input.mp3 -ar 8000 -ac 1 -c:a libopencore_amrnb -b:a 12.2k output.amr

This creates an AMR-NB file at 8 kHz, mono, and 12.2 kbit/s, the highest AMR-NB bitrate. Replace input.mp3 and output.amr with the actual filenames. For speech where file size matters more than quality, use a supported lower bitrate such as 7.4k or 5.9k.

Some FFmpeg packages do not include the libopencore_amrnb encoder. Check for it with ffmpeg -encoders | grep -i amr on macOS or Linux, or ffmpeg -encoders | findstr /i amr on Windows. If it is absent, install an FFmpeg build compiled with AMR-NB encoding support.

Quality and compatibility limits

Conversion cannot restore audio detail discarded during the original MP3 encoding. Re-encoding also applies AMR's speech-focused compression, so an MP3 containing music will not retain its original fidelity. AMR-NB output is normally 8 kHz mono and may be rejected by software that expects AMR-WB, an .awb file, or audio inside a 3GP container. Check the required extension, sampling rate, channel count, and bitrate before sending the converted file.