MP3 to AMR Converter
Upload an MP3 and get back an AMR-NB file at 8 kHz mono, 12.2 kbps, with the #!AMR header that phones and telephony hardware look for. AMR is a speech codec, so voice recordings survive the trip well while music comes back narrow and muffled.
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Why convert MP3 to AMR
MP3 is a general-purpose music format that almost everything plays. AMR-NB, short for Adaptive Multi-Rate Narrowband, is the 3GPP speech codec built for GSM voice calls, and it turns up wherever audio has to be tiny and spoken: voice recorders on older phones, MMS attachments, IVR and PBX prompt slots, alarm and intercom panels, and embedded boards whose firmware parses only one audio format. Those systems usually refuse an MP3 outright, no matter how low its bitrate, which is why the file has to be re-encoded rather than renamed.
On this page the work happens on our servers, not in your browser. ffmpeg decodes the MP3, takes its first audio stream and resamples it to 8 kHz mono 16-bit PCM. That PCM is piped into GStreamer's amrnbenc encoder in mode MR122, the top narrowband mode at 12.2 kbps, and the code writes the #!AMR magic bytes at the start of the file so players and devices identify it correctly. You get one .amr file per MP3, carrying the original base name with the new extension.
Be clear about what the format keeps. At 8 kHz nothing above roughly 4 kHz can exist, so sibilants, cymbals and most of a music track's brightness are gone, and stereo is folded to one mono channel. AMR has no tag container, so ID3 title, artist and album fields are dropped, as is embedded cover art. The bitrate is fixed and the whole file is converted end to end, with no trim option. Most people searching for this are loading spoken audio onto something old or small: phone-system prompts, a voice memo going out by MMS, test fixtures for an Android app that reads .amr. If your source is music and you only wanted a smaller file than the original MP3, convert it to OGG or Opus instead: both sound far better than AMR, though the files are much larger than a 12.2 kbps AMR.
How to convert MP3 to AMR
- Pick the right source. Speech recordings, interviews, voice memos and narration convert well; music comes back narrow and mono.
- Trim first if length matters. This converter encodes the full file with no start or end point, so shorten the MP3 in an audio editor if the receiving device limits duration or file size.
- Add your files. Drag the MP3 onto this page or browse for it. You can queue 10 files per request as a guest or on a free account, 25 on Plus, 50 on Pro.
- Check the size limit: 50 MB per file as a guest, 100 MB with a free account, 200 MB on Plus, 1 GB on Pro. Spoken-word MP3s rarely come close.
- Start the conversion. The file uploads over HTTPS and is queued for a worker; most MP3s of normal length finish within a couple of seconds of the upload completing.
- Download the .amr file and test it on the target device or app. The link stays live for about four hours.
What this converter does
- Writes true AMR-NB with the #!AMR header, so phones, 3GPP players and telephony hardware recognize the file instead of rejecting it.
- Encodes at MR122, 12.2 kbps, the highest AMR-NB mode, rather than one of the lower-rate speech modes.
- Handles the 8 kHz mono step for you: any source sample rate and channel layout is resampled and downmixed before encoding.
- Accepts CBR and VBR MP3s at any bitrate, including 48 kHz files, because the audio is fully decoded before re-encoding.
- Keeps your file name: each upload returns one output named like the input with an .amr extension, so batches of recordings stay easy to match up.
- Works from any browser with no account and no install for files inside the guest limits — the encoding itself runs on our servers.
Frequently asked questions
Can I get AMR-WB (wideband) output instead?
No. This page produces AMR-NB only, and renaming the file will not change the codec inside. You would need a tool that exposes a wideband encoder, or check whether the receiving system also accepts AMR-NB, which most AMR-capable hardware does.
Why does my music sound muffled and flat?
That is the codec, not a setting we got wrong: AMR models the human voice rather than instruments, caps the audio at about 4 kHz and collapses stereo to mono. For music, convert the MP3 to OGG or Opus instead. For speech, AMR is doing what it was designed for.
Can I choose the bitrate or quality?
No. There is no quality, bitrate or sample-rate selector on this page: every file is encoded in the format's best narrowband mode, which is as good as AMR-NB gets. No volume normalization or noise reduction is applied either.
How many MP3s can I convert at once?
Up to 10 files in one batch as a guest or on a free account, 25 on Plus and 50 on Pro. Each file is converted and downloaded separately; there is no combined ZIP download and no option to merge several MP3s into one AMR.
Will my title, artist and album tags survive?
No. The AMR bitstream has no metadata container, so ID3 tags and embedded cover art are not carried into the output. Only the file name follows the conversion, so keep your tagged MP3 if you still need that information.
The conversion failed with ERROR_AUDIO_AMR_ENCODE. What now?
That message means the GStreamer AMR encoder failed or produced no frames. It is rare: one file in the last 90 days. A retry often clears it; if it does not, convert the MP3 to WAV first and then convert that WAV to AMR, or re-export the MP3 from your editor.
Can I turn the AMR file back into an MP3 later?
Yes, we have an AMR to MP3 converter, and AMR files can also be converted here to WAV, OGG, FLAC, AAC, M4A, AIFF and Opus. The quality loss is one-way, though: the high frequencies and the second channel cannot be restored.
What happens to my files after the conversion?
Conversion runs on our servers. Your uploaded MP3 is deleted as soon as the job finishes, and the AMR can be downloaded for about four hours before it is deleted automatically. The download link is a long random token, is not single-use and is not tied to your account, so treat it as private. File names, sizes and outcomes are logged for diagnostics, and signed-in users keep a history row.