AAC to FLAC Converter — Free, Online, No Upload

AAC is a widely distributed format — Apple Music, iTunes purchases, YouTube audio, and many podcast feeds deliver audio in AAC. The problem is that the hardware and software designed for serious listening often speaks only FLAC. Audiophile DACs from brands like Chord, iFi, and Schiit, network streamers from Naim, Cambridge, and Bluesound, and music server software like Roon and JRiver Media Center are built around lossless formats (FLAC and WAV) and frequently won't mount or play an AAC or M4A file at all.

Converting AAC to FLAC is the compatibility bridge that makes those files readable on lossless-first hardware. The FLAC stores the decoded AAC audio without any further encoding — no additional quality loss beyond what the original AAC compression already introduced. The format switch unlocks playback on hi-fi equipment that would otherwise reject the file entirely. FLAC also handles metadata far more reliably in audiophile software than AAC's MP4 container tags.

It's important to be clear about what doesn't happen: the conversion does not make the audio lossless. FLAC is a lossless codec wrapping a lossy source. Listeners won't hear quality improvement over the AAC original — they'll hear the same audio, now accessible on hardware that previously couldn't play it. If true lossless audio is the goal, the original recording must be sourced from a lossless master, not re-encoded from AAC.

Typical sizes (3-minute song): AAC 2–5 MB → FLAC 20–40 MB.

FLAC will not restore detail the AAC encoder removed, and the file gets bigger.