AMR to AU Converter
Processing entirely on your device — large files may take a moment.
Converting AU to WAV preserves the samples in a format every modern tool reads. If your files are still in AMR format, this page is the shortcut: AMR is the tiny voice-recording format of old Nokia-era phones and answering machines.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How AMR compares to AU
| AMR | AU | |
|---|---|---|
| Compression | Lossy speech codec | µ-law or PCM |
| Quality | Speech only | Mono voice-grade (µ-law) |
| Compatibility | Phone recorders | Legacy Unix tools |
| Best for | Voice memos and call recordings | Old system sounds and recordings |
How to convert AMR to AU
- 1
Select your files
Drag & drop your AMR files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to AU". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted AU file individually, or grab everything at once as a ZIP archive.
About the AMR format
AMR (Adaptive Multi-Rate) is the speech codec of 2G/3G telephony, and the default recording format of countless feature phones and early smartphones. It is optimized exclusively for human voice: narrowband (300–3400 Hz) and wideband (AMR-WB, 50–7000 Hz) modes that make calls sound like calls.
For voice memos it is remarkably compact — a few kilobits per second. For anything musical it is hopeless: cymbals, bass and anything above its band simply do not exist. Convert AMR voice notes to MP3/Opus for archiving and playback anywhere else.
+ Strengths
- ✓Extremely compact for speech
- ✓Native phone-recorder format
! Limitations
- −Voice-only: music quality is unusable
- −Narrow bandwidth sounds dated
About the AU format
AU is Sun Microsystems' audio format from the Unix workstation age: a small header followed by µ-law (or PCM) samples. Java's applet era shipped it everywhere, and old Unix sound tooling still emits it.
Modern players increasingly skip it. Converting AU to WAV preserves the samples bit-for-bit while moving the file into universal territory — the standard rescue path for system sounds and old recordings.
+ Strengths
- ✓Simple, lossless sample storage
- ✓Native to old Unix/Java tooling
! Limitations
- −µ-law flavor sounds dated and mono
- −Dropped by modern players
Why convert AMR to AU?
Converting makes sense where the strengths of AU meet what AMR cannot give you. Simple, lossless sample storage Meanwhile Voice-only: music quality is unusable One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this AMR to AU converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for AMR to AU?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will converting AMR to AU reduce audio quality?
If AU is lossless, the output contains everything the AMR file contains — no further loss is added. If AU is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.