Free online AMR to AAC converter

Older phones, voicemail systems, and telecom exports may produce AMR recordings that a media player, editor, or upload service will not accept. AAC is more widely supported, but conversion only repackages the existing speech quality into a different lossy codec.

What AMR files contain

AMR (Adaptive Multi-Rate) is a lossy speech codec developed for mobile telephony. Standard AMR-NB files normally use the .amr extension and contain mono narrowband speech at 8 kHz; AMR-WB, often saved as .awb, supports 16 kHz wideband speech.

AMR was used by GSM and 3G mobile networks, older mobile phones, voice recorders, voicemail platforms, and telecom equipment. Its low bitrates preserve speech intelligibility efficiently, but it is not intended for music or recordings requiring high-frequency detail.

What AAC files contain

AAC (Advanced Audio Coding) is a lossy codec supported by current phones, media players, video editors, and MP4-based workflows. It is suitable for speech and music and is generally more broadly accepted than AMR outside telecom systems.

AAC can be stored as a raw .aac stream, usually with ADTS framing, or inside an MP4 audio container using the .m4a extension. Use the extension required by the receiving program. Many desktop and mobile applications accept AAC only when it is packaged as .m4a.

Convert the file

Upload the AMR file to 101convert.com, select AAC as the output format, start the conversion, and download the converted file. If the destination specifically requests an M4A file, choose an M4A/AAC output option when available rather than a raw .aac file.

For local, repeatable conversion, FFmpeg can create an M4A file containing AAC audio:

ffmpeg -i input.amr -c:a aac -b:a 48k output.m4a

To create a raw AAC stream instead, use:

ffmpeg -i input.amr -c:a aac -b:a 48k -f adts output.aac

For AMR-NB speech, 32–48 kb/s mono is normally sufficient. Preserve mono output and the source sample rate where the converter permits it; turning an 8 kHz recording into stereo or resampling it to 44.1 kHz does not add audio detail.

Quality and compatibility limits

AMR-to-AAC conversion is lossy-to-lossy. A higher AAC bitrate can reduce additional encoding damage, but it cannot restore frequencies or clarity removed by the original AMR encoding; encoding narrowband speech at 128 kb/s mainly increases file size.

If an application rejects .aac, try .m4a. Keep the original AMR file when it is the source record, because each subsequent AAC export adds another lossy generation.