AMR vs WMA
A detailed comparison of AMR Audio and Windows Media Audio — file size, quality, compatibility, and which format to choose for your workflow.
AMR Audio
Audio FilesAMR (Adaptive Multi-Rate) is an audio format optimized for speech, used in phone calls.
About AMR filesWindows Media Audio
Audio FilesWMA is a proprietary Microsoft audio format from the Windows Media framework. Once common in the Windows ecosystem, it has been largely replaced by AAC and MP3 for general use.
About WMA filesStrengths Comparison
AMR Strengths
- Extremely low bitrate — 4.75-12.2 kbps for speech.
- Designed for error-prone mobile channels — handles packet loss gracefully.
- Tiny file sizes — hours of voice in a few MB.
- Mandatory codec in all 3G/UMTS phones — universal cellular compatibility.
WMA Strengths
- Good quality at low bitrates (32-64 kbps) — outperformed MP3 in that range.
- Native playback on every Windows version 2000 through 10.
- Lossless variant available (WMA Lossless) for archiving.
- Supports multichannel 5.1 surround audio.
Limitations
AMR Limitations
- Speech-only — music sounds distorted.
- Narrowband (8 kHz sample rate) — muffled compared to modern codecs.
- Patent-encumbered until recently — licensing fees slowed adoption outside telephony.
- Being phased out of new devices in favor of EVS and Opus.
- Non-standard extensions and variants make tooling inconsistent.
WMA Limitations
- Proprietary — poor support outside Windows and Windows Media Player.
- DRM variants made files brittle — many purchased tracks became unplayable when stores shut down.
- Ecosystem abandoned — no modern editors, hardware decoders, or streaming services use WMA.
- Windows 11 deprecated Windows Media Player entirely.
Technical Specifications
| Specification | AMR | WMA |
|---|---|---|
| MIME type | audio/amr | audio/x-ms-wma |
| Extensions | .amr, .3ga | — |
| Standard | 3GPP TS 26.071 (narrowband), TS 26.171 (wideband) | — |
| Sample rate | 8 kHz (AMR-NB); 16 kHz (AMR-WB) | — |
| Bitrates | 4.75, 5.15, 5.9, 6.7, 7.4, 7.95, 10.2, 12.2 kbps | — |
| Extension | — | .wma |
| Container | — | ASF (Advanced Systems Format) |
| Variants | — | WMA Standard, WMA Pro, WMA Lossless, WMA Voice |
| Max bitrate | — | 768 kbps (WMA Pro) |
Typical File Sizes
AMR
- 1-min voice memo 45-90 KB
- 1-hour voicemail archive 3-5 MB
WMA
- 3-min song (128 kbps) 3 MB
- 3-min song (Lossless) 25-35 MB
- 1-hour talk (64 kbps) 28 MB
Ready to convert?
Convert between AMR and WMA online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
AMR (AMR Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
WMA (Windows Media Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
VLC, foobar2000, and the default media players on Windows and macOS handle AMR natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
VLC, foobar2000, and the default media players on Windows and macOS handle WMA natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
Upload the AMR to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.
AMR can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.