Convert AAC to FLAC
Free online converter for AAC files. Lossless compression with roughly half the size of WAV. Nothing to install, no watermark, and every file is deleted automatically.
Drag and drop your files
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Upload a AAC file to convert it to FLAC. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About AAC and FLAC
AAC .aac
MP3's designated successor, and the default in the Apple ecosystem and most streaming services. Better sound than MP3 at the same bitrate.
Good for
- Noticeably better than MP3 at equal bitrates
- The default across Apple devices and most streaming
- Handles multichannel audio properly
Trade-offs
- Lossy
- Patent licensing is more involved than Opus or Vorbis
audio/aac
FLAC .flac
Lossless compression for audio. Roughly half the size of WAV, and it decodes back to the original samples exactly — nothing is approximated.
Good for
- Perfect reconstruction — identical to the source
- Around 50–60% of the size of WAV
- Full tagging, and an open royalty-free format
Trade-offs
- Still far larger than MP3 or AAC
- Not supported by every portable player or car stereo
audio/flac
AAC and FLAC side by side
| AAC | FLAC | |
|---|---|---|
| Compression | Lossy | Lossless |
| Typically used for | Streaming, Apple devices, video soundtracks | Archiving, high-fidelity libraries |
What changes when you convert AAC to FLAC
This is a re-encode, not a repackage
Some tools can move a stream into a different container untouched when the codecs happen to line up. We do not — every job here is decoded and encoded again, so the conversion takes time in proportion to the length of the file and costs a small amount of quality even where a repackage would have been possible. In exchange the output is predictable: it plays everywhere, rather than inheriting whatever the source happened to contain.
What your FLAC will contain
The output is FLAC — which is lossless, so there is no bitrate to set — the size is decided entirely by how compressible your audio turns out to be, usually landing near half of the equivalent WAV while preserving every sample exactly.
Quality cannot come back
AAC already discarded detail permanently, and FLAC stores exactly what it is given. The result will be considerably larger while sounding identical to the AAC you started from — lossless preserves, it does not restore. That is still the right move if you are about to edit, because further saves will not degrade it again.
Tags may not survive intact
AAC stores its metadata as ID3, and FLAC uses Vorbis comments. Standard fields such as title, artist and album normally map across. Anything without an equivalent on the other side — unusual custom fields, some ratings and play counts, occasionally embedded artwork — has nowhere to go. Check the tags before deleting the original if your library depends on them.