FLAC to AMR Converter

FLAC to AMR Converter

AMR is the speech codec built for mobile telephony, and .amr is the plain file wrapper defined for it in RFC 4867 — a nine-byte magic header (#!AMR\n) followed by one small frame every 20 milliseconds. FLAC is the opposite: a lossless archive format that keeps every sample of a full-bandwidth recording. Converting one to the other is a deliberate, large downgrade, and it is worth doing only when something specifically demands .amr: a voicemail or IVR platform, an MMS gateway, a feature phone, a police or dispatch recorder, or an embedded device with a fixed decoder.

Speech survives this well. Music does not — AMR narrowband models the human vocal tract inside the 200–3,400 Hz telephone band, so instruments and cymbals have nowhere to go. If you only want smaller music files, a general-purpose lossy codec is the right target instead; see the escape hatches further down this page.

AMR Narrow Band and AMR Wide Band Compared

Both appear under Audio Codec on this page. They are different codecs, not quality settings of one codec, and the file header differs too.

Pick Narrow Band when you need the file to open anywhere. Pick Wide Band only when you know the receiving system handles wideband AMR — plenty of legacy telephony gear does not.

What Each Quality Preset Produces

AMR does not accept arbitrary bitrates: every frame must use one of the codec's defined modes, so the encoder snaps your request to the nearest legal mode. These are the modes each Quality Preset lands on, with the size one minute of audio produces at each:

Because AMR-NB has only eight modes and they bunch together at the top, Very High and High both resolve to the 10.20 kbps mode. For dictation, voicemail and IVR prompts, the 12.20 kbps mode (Highest) is the usual choice — it is the mode most telephony systems assume.

How to Convert FLAC to AMR

1. Upload Your FLAC File: Drag and drop your .flac file onto the page or click "+ Add Files". Several files can be queued and converted with the same settings.
2. Pick the Audio Codec: Under Audio Codec, choose AMR Narrow Band for the standard 8 kHz .amr that phones and telephony systems expect, or AMR Wide Band when the target device supports 16 kHz wideband speech.
3. Choose a Quality Preset, then check Channel and Sample Rate: Set Quality Preset from the table above. Audio Channel offers MONO only and Audio Sample Rate offers 8000 HZ and 16000 HZ, because the codec fixes both — narrowband is always 8 kHz mono, wideband always 16 kHz mono. Use Trim if you only need part of the recording.
4. Convert and Download: Click Convert and download the .amr. Files are uploaded over an encrypted connection, converted on our servers, and deleted automatically a few hours later — no sign-up, no watermark.

When AMR Is the Wrong Target

If nothing in your chain literally requires .amr, almost any other codec will serve you better at the same size. Modern speech encoders reach comparable intelligibility with far more headroom, and general-purpose formats give you stereo and full bandwidth back. Use FLAC to MP3 for maximum device compatibility, FLAC to M4A for Apple libraries, or FLAC to OGG for an open, royalty-free option. Keep the FLAC as the master either way — nothing recovers what AMR discards.

Frequently Asked Questions

Why does my music sound thin and warbly as AMR?

Because AMR is not a music codec. It is a code-excited linear prediction (CELP) speech coder: instead of storing the waveform, it fits a model of a human vocal tract to the signal frame by frame. Anything that is not a voice — drums, strings, reverb tails, cymbals — has no representation in that model, so the encoder produces the closest "voice-like" approximation it can. Add the 200–3,400 Hz narrowband limit and music simply cannot survive. Spoken word, by contrast, comes through clearly.

Why is the output mono at 8 kHz when my FLAC is 44.1 kHz stereo?

Because AMR-NB is defined as a single-channel, 8 kHz codec — there is no stereo or high-rate variant. The converter downmixes to mono and resamples to 8,000 Hz so the result is a valid .amr file that decoders will accept. AMR Wide Band raises this to 16 kHz but is still mono. That is the format, not a limitation of the tool.

What is the difference between the .amr file and a raw AMR stream?

RFC 4867 defines the file storage format: a magic string, then the coded frames back to back. Our output starts with the exact bytes 23 21 41 4D 52 0A (#!AMR\n) for narrowband or 23 21 41 4D 52 2D 57 42 0A (#!AMR-WB\n) for wideband, which is how players and gateways identify which codec is inside. A raw stream without that header will be misread — if a tool rejects your file, checking the first bytes in a hex viewer is the fastest diagnosis.

How much smaller is the AMR than my FLAC?

Dramatically smaller — around 98% smaller for typical speech. In our testing a 60-second 44.1 kHz stereo FLAC of 4,772,184 bytes converted to a 96,038-byte AMR-NB file at the 12.20 kbps mode, and 183,009 bytes as AMR-WB at 23.85 kbps. AMR is constant-rate per mode, so the size is set purely by duration: roughly 92 KB per minute at 12.20 kbps and 179 KB per minute at 23.85 kbps, regardless of what is being said.

Do the title, artist and other tags carry over into the AMR?

No. The .amr storage format has no metadata area at all — it is a magic header followed by speech frames, with nowhere to put a title or cover art. Anything stored in the FLAC's Vorbis comments is dropped. If you need tags to survive, choose a container format such as M4A or MP3 instead.

Can I convert the AMR back to FLAC afterwards and recover quality?

You can convert it back with AMR to FLAC, but the audio will not improve. FLAC losslessly stores whatever it is given, so you would get a bit-perfect copy of the degraded 8 kHz mono speech in a much larger file. Everything AMR removed — the stereo image, the frequencies outside the telephone band, the waveform detail replaced by the CELP model — is gone for good. Always keep the original FLAC.

Which players and devices open .amr files?

VLC, foobar2000, Audacity and most Android phones open .amr directly. Windows and macOS often will not play it with the stock media player, and Apple's ecosystem is inconsistent about it. That, ironically, is one of the better reasons to avoid AMR unless a specific system asks for it — the format's home is telephony infrastructure, not desktop playback. If you need to hand the file to someone who just wants to listen, send them AMR to MP3 output instead.

How is my upload handled, and how long do you keep it?

Your file is uploaded over an encrypted connection and converted on our servers; the upload and the result are both deleted automatically a few hours later. Nothing is shared or made public, there is no sign-up, and no watermark is added. AMR output is tiny, so the only slow part of the process is sending the lossless FLAC up in the first place.