Convert your audio files, especially voice recordings, to the AMR (Adaptive Multi-Rate) format using our free online tool. AMR is optimized for speech coding and used extensively in mobile telephony (GSM, 3G). Convert from WAV, MP3, AAC, etc., to AMR for compatibility or size reduction of voice data. The service is secure (files deleted within about an hour), free, and requires no user account.
Creating AMR files is simple:
AMR from the 'Convert to:' dropdown list. (Note: AMR exists as AMR-NB (Narrowband) and AMR-WB (Wideband); our converter always writes AMR-NB at 12.2 kbps, 8 kHz mono).
AMR (Adaptive Multi-Rate) is an audio data compression format optimized for speech coding. It was adopted as the standard speech codec by 3GPP in 1999 and is now widely used in GSM and UMTS mobile networks. AMR files typically have the .amr extension.
AMR uses link adaptation to select from one of eight different bit rates based on channel conditions, aiming to maintain acceptable speech quality even in poor network environments. It exists in two main variants:
AMR is highly efficient for voice but not generally suitable for music or complex audio due to its speech-focused design.
AMR files are most commonly encountered from mobile phone voice recorders or messaging apps. Playback support varies:
For desktop use, VLC is a reliable option. If compatibility is an issue, converting AMR files to a more standard format like MP3 or WAV might be necessary.
| Full name | Adaptive Multi-Rate Narrowband |
|---|---|
| Compression | Lossy (speech) |
| Developed by | 3GPP |
| Introduced | 1999 |
| File extension | .amr |
| Typically used for | Call recordings, old mobile voice memos, MMS |
| Plays on | Android, VLC, many phones; poor browser support |
| Our output | AMR-NB, 12.2 kbps, 8 kHz mono |
We create AMR-NB (narrowband) at 12.2 kbps, its highest bitrate mode, with an 8 kHz sample rate in mono. AMR-WB (wideband) output is not available. AMR-NB is the classic mobile phone speech codec, so it plays on the widest range of phones and telephony systems that accept .amr files.
It isn't a good idea. AMR-NB samples at 8 kHz, which means nothing above about 4 kHz survives, and the codec is tuned for the human voice. Music comes out muffled and phone-like. Use AMR only for speech such as voice notes, interviews or telephone prompts, and choose MP3, M4A or Opus for music.
Very small. At 12.2 kbps an AMR file uses about 0.09 MB per minute, so an hour of speech is only around 5.4 MB. That is roughly a sixteenth of the size of a 192 kbps MP3, which is why AMR suits long voice recordings and low-storage devices.
Most Android phones play AMR, since many voice recorder apps have used it, and VLC plays it on Windows, Mac, Linux, iOS and Android. FFmpeg-based tools also handle it. Many desktop music apps don't support AMR, so if someone can't open the file, suggest VLC or send an MP3 instead.
It is downmixed to mono and resampled to 8 kHz, so stereo width and high frequencies are removed and the result sounds like a phone call. That is expected for AMR-NB. If you want a small voice file that still sounds natural, Opus or MP3 keeps far more detail.
Typical reasons are telephony systems and voicemail or IVR platforms that accept only AMR prompts, older and basic phones that play AMR but not much else, and apps that ask for .amr uploads. It is also a way to keep very long speech recordings tiny, as long as phone-call quality is acceptable.
Need detailed information or want to set a different default format? Visit our specific converter pages: