M4A to AMR Converter
Initializing... drag & drop files here
Supports: M4A
Advanced Options - Our defaults are optimized for the best results. We recommend you keeping the defaults unless you have a specific need.
Reset to defaults
Need help?How to Convert M4A to AMR Online
- Upload Your M4A Files: Drag and drop or click "Add Files" to select M4A audio from your computer. Voice memos from iPhone, GarageBand exports, Apple Voice Memos, Audible chapter rips, and AAC podcast clips all work. Batch upload is supported.
- Pick the AMR Codec: Default is AMR-NB (narrowband, 8 kHz) — the codec used by GSM voicemail, 2G/3G handset ringtones, and MMS attachments. Switch to AMR-WB (wideband, 16 kHz) for HD voice / VoLTE recordings and modern IVR systems that accept .awb. Pick a constant bitrate (4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, or 12.2 kbps for AMR-NB; 6.60-23.85 kbps for AMR-WB) — 12.2 kbps is the GSM full-rate standard.
- Set Sample Rate, Channels, and Trim (Optional): AMR-NB locks to 8000 Hz mono and AMR-WB locks to 16000 Hz mono — this is by design for the codec. Use the trim section to enter a start time and duration in HH:MM:SS.sss format if you only need a short ringtone clip or a MMS-friendly excerpt.
- Convert and Download: Click Convert. Files process in your browser session and download individually or as a ZIP — no sign-up, no watermark, no upload to a third-party server.
Why Convert M4A to AMR?
M4A is Apple's MPEG-4 audio container — typically AAC at 128-256 kbps, occasionally ALAC lossless — designed for music, podcasts, and audiobooks. AMR (Adaptive Multi-Rate) is a parametric speech codec built by Ericsson and Nokia in the late 1990s, adopted by 3GPP for GSM/UMTS voice calls. It throws away everything outside the speech band (300 Hz - 3.4 kHz for AMR-NB) and compresses voice down to ~100 KB per minute. Common reasons to convert M4A → AMR:
- Legacy ringtones for older phones — Nokia, Sony Ericsson, BlackBerry, and pre-iOS Symbian/Java handsets still in service across parts of Asia, Africa, and rural networks expect .amr ringtones, not .m4a or .mp3. AMR is the only universally accepted ringtone format on 2G/3G feature phones.
- MMS audio attachments — MMS gateways across most carriers cap audio attachments at ~300 KB and require AMR-NB. A 30-second M4A voice memo is 500 KB+; the same clip as AMR-NB is ~50 KB and goes through cleanly.
- IVR and voicemail prompt uploads — Asterisk, FreePBX, Twilio, and most enterprise IVR platforms accept AMR for prompt uploads, hold music exclusions, and voicemail greetings. Some legacy telephony stacks reject M4A entirely.
- Embedded systems and IoT voice prompts — automotive head units, industrial alarm panels, and low-power IoT speakers often decode AMR in hardware but lack AAC support. Converting prompts to AMR keeps firmware size down.
- Dumbphone voice messages — KaiOS phones (JioPhone, Nokia 8110), Light Phone, and the recent feature-phone revival accept AMR voice messages but not Apple's M4A.
- Forensic and compliance archival of call samples — telecom regulators in some jurisdictions require audio submitted for review to be in the codec actually transmitted (AMR), not a transcoded high-fidelity format.
See also M4A to MP3 for music-friendly output, or AMR to WAV for going the other direction to edit existing AMR recordings.
M4A vs AMR — Format Comparison
| Property | M4A (AAC) | AMR |
|---|---|---|
| Codec family | AAC-LC / HE-AAC / ALAC (lossless) | ACELP-based parametric speech codec |
| Typical bitrate | 96-256 kbps (AAC), 600-1100 kbps (ALAC) | 4.75-12.2 kbps (NB), 6.6-23.85 kbps (WB) |
| Sample rate | 8 kHz to 96 kHz, freely selectable | 8 kHz only (NB) or 16 kHz only (WB) |
| Channels | Mono, stereo, 5.1, 7.1 | Mono only |
| 1-minute file size | ~1-2 MB at 128 kbps stereo | ~50-100 KB |
| Frequency range | 20 Hz - 20 kHz+ (full audible) | 300 Hz - 3.4 kHz (NB) / 50 Hz - 7 kHz (WB) |
| Best for | Music, podcasts, audiobooks, iTunes | Voice calls, voicemail, MMS, ringtones for 2G/3G |
| Hardware support | iPhone, Android, iTunes, QuickTime | GSM/UMTS handsets, IVR, VoLTE devices |
AMR Bitrate Quick Guide
| AMR mode | Bitrate | Sample rate | Best for |
|---|---|---|---|
| AMR-NB 4.75 kbps | 4.75 kbps | 8 kHz | Smallest files — barely-intelligible MMS where size matters more than clarity |
| AMR-NB 7.40 kbps | 7.40 kbps | 8 kHz | Half-rate GSM voice — adequate speech, very small |
| AMR-NB 12.2 kbps | 12.2 kbps | 8 kHz | Default — GSM full-rate, equivalent to old GSM-EFR call quality |
| AMR-WB 12.65 kbps | 12.65 kbps | 16 kHz | HD-voice intelligibility at NB-comparable size |
| AMR-WB 15.85 kbps | 15.85 kbps | 16 kHz | Common VoLTE / 3GPP HD voice setting |
| AMR-WB 23.85 kbps | 23.85 kbps | 16 kHz | Maximum AMR-WB quality — clearest speech, largest AMR files |
Important: Quality Reduction is Permanent
AMR is a destructive lossy codec optimized exclusively for the human voice. Converting a music M4A to AMR will strip out all bass below 300 Hz, all high frequencies above 3.4 kHz (AMR-NB) or 7 kHz (AMR-WB), and apply a vocal-tract model that mangles non-speech audio. This is not a quality issue with the converter — it's how AMR works by design. Use M4A to AMR only when the destination device or system requires AMR. For music or general listening, convert M4A to MP3 or keep it as M4A.
Frequently Asked Questions
Should I pick AMR-NB or AMR-WB for my output?
Match the destination. AMR-NB (8 kHz) is the right choice for ringtones on older feature phones, MMS attachments to 2G/3G handsets, and any system that pre-dates 2010. AMR-WB (16 kHz, sometimes saved as .awb) is required for VoLTE / HD-voice systems, modern IVR platforms, and 3GPP-compliant wideband recordings. If you're not sure, AMR-NB at 12.2 kbps is the safest universal default — every AMR decoder on the planet handles it.
Why does my converted AMR sound so bad compared to the original M4A?
That's expected. M4A typically carries AAC at 128 kbps stereo with a full 20 Hz - 20 kHz frequency range. AMR-NB throws that down to 12.2 kbps mono and a 300 Hz - 3.4 kHz band — a 10× compression ratio plus aggressive frequency truncation, with a codec model designed for voice rather than music. Drums, cymbals, bass, and any pitched instrument come through badly. This is by design; AMR is for speech only.
Can I make ringtones for my iPhone in AMR?
No — iPhone ringtones use M4R (M4A renamed) and require AAC. Convert M4A to AMR only for non-Apple legacy phones (Nokia, Sony Ericsson, JioPhone, KaiOS feature phones, older Android devices) or for MMS / IVR systems. For iPhone ringtones, use M4A to M4R instead.
How long can my AMR clip be for an MMS attachment?
Most carriers cap MMS payload at ~300 KB total (which must include any attached image plus the audio plus headers). At AMR-NB 12.2 kbps that's roughly 3 minutes of audio, but in practice keep clips to 30-60 seconds to stay under aggregate limits. At 4.75 kbps you can fit ~7 minutes in 300 KB — useful for voicemail-style MMS where intelligibility matters more than clarity.
Will my M4A's stereo mix become mono in the conversion?
Yes — AMR is mono-only at the codec level. The encoder downmixes left and right channels to a single mono track before encoding. If your source M4A has critical stereo information (e.g., a dialogue panned hard right), pre-mix it to center in an editor before converting, otherwise the panned audio attenuates by 3 dB during downmix.
Can I batch convert a folder of voice memos to AMR for an old phone's voicemail upload?
Yes. Drop in dozens of .m4a voice memos at once. Each file converts in parallel within your browser session and downloads as individual AMRs or a single ZIP. Useful for migrating an iPhone Voice Memos folder to a Nokia / KaiOS feature phone or for bulk-uploading IVR prompts to an Asterisk server.
Does the converter handle ALAC (Apple Lossless) M4A files?
Yes. M4A is just a container — the underlying audio can be AAC (most common, from iTunes, Voice Memos, podcasts) or ALAC (Apple Lossless, often from CD rips). Both decode correctly and re-encode to AMR. ALAC sources are first decoded to PCM, then downmixed to mono and encoded as AMR; the final file size is identical regardless of source codec because AMR's bitrate is fixed.
Will my AMR file play on iPhone or Android?
Modern iPhones do not natively play .amr files — you need VLC for iOS or a third-party AMR player. Android historically supports AMR via the system media framework, though support has been deprecated on Android 13+ in some OEM builds. AMR is intended for the destination device or telephony system, not for playback on smartphones — for general phone playback, convert M4A to MP3 or keep it as M4A instead.