AU to FLAC converter
Convert AU to FLAC 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 FLAC, add the AU file to the iHateFiles AU to FLAC 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. FLAC is not.
Should you convert AU to FLAC?
A safe conversion: AU and FLAC are both lossless, so the sound is identical and only the file changes.
Every sample survives
AU and FLAC are both lossless, so the FLAC decodes to exactly the same samples as the AU. Only the packaging changes: up to 10 MB per minute as AU, 5 to 7 MB as FLAC.
Where the FLAC will play
FLAC plays on VLC, Android, Windows 10 and later, and recent Macs.
AU and FLAC side by side
| AU | FLAC | |
|---|---|---|
| Inside the file | PCM or µ-law | FLAC |
| Compression | Lossless | Lossless |
| Carries sound | Yes | Yes |
| One minute of stereo | up to 10 MB | 5 to 7 MB |
| Plays on | Needs converting first | VLC, Android, Windows 10 and later, and recent Macs |
| 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 FLAC. Converting an MP3 to FLAC produces a large file that sounds exactly like the MP3. Lossless compression preserves what it is given, including the damage.
How to convert AU to FLAC
- Add your AU file. It is read from your disk and stays there.
- Check the settings. The output format is already set to FLAC.
- Press convert and the FLAC file is saved back to your device.
Questions
How do I convert AU to FLAC?
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 FLAC 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 FLAC lose quality?
FLAC is lossless, so this step throws nothing away. If the original was already a lossy format, the damage it did cannot be undone, but nothing further is lost.
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.