AAC to FLAC Converter
Convert AAC to FLAC free — no upload, no signup
To convert AAC to FLAC, drop your AAC audio files into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. Store AAC losslessly as FLAC for systems that need it.
Drop audio files here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
FLAC is lossless — no bitrate to choose. Sample rate and channels are under Advanced.
Advanced
How to convert AAC to FLAC
Add your AAC files
Drag and drop AAC files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Check the settings
FLAC is lossless, so there's no bitrate to pick. Change sample rate or switch to mono under Advanced if a device needs it.
Convert and download
Click Convert, then download each FLAC file or all of them as one ZIP.
Why convert AAC to FLAC?
Some archive systems and hi-fi players only accept FLAC.
What happens when you convert AAC to FLAC?
The decoded AAC is saved losslessly in FLAC, several times larger than the AAC.
How does Fylo convert AAC to FLAC?
Fylo decodes the AAC audio in the AAC with ffmpeg compiled to WebAssembly and encodes it with FLAC lossless compression. Nothing is added back: the FLAC is an exact but larger copy of the decoded AAC (≈ 18–24 MB for a 3-minute song versus ≈ 3.6 MB at 160 kbps). The original sample rate and channel layout are kept unless you change them under Advanced.
What's the difference between AAC and FLAC?
AAC (Advanced Audio Coding) was standardised in 1997 as part of MPEG-2 and later MPEG-4, designed to replace MP3. It achieves better quality at the same bitrate, especially below 128 kbps. A .aac file is usually a raw ADTS stream; the same audio inside an MP4 container is called M4A.
FLAC (Free Lossless Audio Codec) was released in 2001 and later maintained by the Xiph.Org Foundation. It compresses PCM audio like a ZIP file compresses data: nothing is thrown away, so a FLAC decodes to exactly the same samples as the source WAV, typically at 50–70% of the size.
Learn more: AAC format guide · FLAC format guide
| Property | AAC | FLAC |
|---|---|---|
| Compression | Lossy | Lossless |
| Typical bitrate | 96–256 kbps | ≈ 700–1,100 kbps |
| 3-minute song | ≈ 3.6 MB at 160 kbps | ≈ 18–24 MB |
| Tags and cover art | Limited in raw .aac (full in M4A) | Yes (with cover art) |
| Compatibility | Very wide: Apple, Android, YouTube, browsers | Android, Windows 10+, macOS, most players and hi-fi gear |
| Best for | Efficient music and video soundtracks | Archiving music without quality loss |
| Introduced | 1997 | 2001 |
Frequently asked questions
Does converting AAC to FLAC improve quality?
No. AAC is lossy, so detail removed during its compression can't be restored. The FLAC is a lossless copy of what the AAC sounds like — bigger, but not better.
Is this useful for archiving?
Only if the system requires FLAC; the original AAC is already the best copy.
Is my AAC file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your AAC file is read directly from your device and never sent anywhere.
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