AU to MP3 converter
Convert AU to MP3 in seconds, free and unlimited. No upload, no sign-up, no watermark: your audio never leaves your device.
Last updated
Quick answer: To convert AU to MP3, add the AU file to the iHateFiles AU to MP3 converter and press Convert. The conversion runs in your browser, so the file is never uploaded, and it is free with no sign-up, watermark or size limit. AU is a format most software has stopped opening. MP3 is not.
Should you convert AU to MP3?
Do this to make a lossless recording small enough to share or carry around. Keep the AU as the master copy.
AU is lossless and MP3 is not
This is the conversion lossy formats were designed for: from up to 10 MB per minute to 1 to 2.4 MB. At 192 kbps or more almost nobody can hear the difference in music. Keep the AU as your master if you might need to convert again.
Where the MP3 will play
MP3 plays on everything, including car stereos and hardware twenty years old.
AU and MP3 side by side
| AU | MP3 | |
|---|---|---|
| Inside the file | PCM or µ-law | MPEG-1 Layer III |
| Compression | Lossless | Lossy |
| Carries sound | Yes | Yes |
| One minute of stereo | up to 10 MB | 1 to 2.4 MB |
| Plays on | Needs converting first | everything, including car stereos and hardware twenty years old |
| Here | Read only | Read and write |
What usually goes wrong
About the AU. Many AU files use 8-bit µ-law companding, which sounds like a telephone. That is how they were recorded, not a conversion fault.
About the MP3. Converting an MP3 to another lossy format compounds the damage, because the second encoder is guessing at audio the first one already threw away.
How to convert AU to MP3
- Add your AU file. It is read from your disk and stays there.
- Check the settings. The output format is already set to MP3.
- Press convert and the MP3 file is saved back to your device.
MP3 converter: everything that converts to MP3
Questions
How do I convert AU to MP3?
Open this page, add your AU file, and press convert. The file is decoded and re-encoded by your own browser and saved back to your device. Nothing is uploaded.
Is this AU to MP3 converter free?
Yes, completely. There is no account, no sign-in, no watermark and no daily limit, because there is no server doing the work. Your own device does it.
Are my files uploaded anywhere?
No. There is no upload endpoint. The conversion runs inside this browser tab, so your file never leaves your device. You can open your browser's network panel and watch: nothing carrying your file is sent.
Is there a file size limit?
No fixed limit. Because the work happens on your machine there is no server quota. The only ceiling is your own device's memory, which for video means very large files may be slow.
Will converting to MP3 lose quality?
MP3 is a lossy format, so some detail is discarded. The quality control on this page decides how much. The default is set high enough that most people cannot see the difference.
Can I convert several AU files at once?
Yes. Add as many as you like and they are converted one after another, then offered as a single ZIP.