Convert AAC to FLAC
Convert AAC audio files to FLAC lossless format directly in your browser. FLAC locks in a stable archival master with no further generational loss during editing or re-encoding. No upload needed.
Drag 'n' drop files here, or
click to select files
.aac, .m4a
Drop your files and click Convert to get FLAC
//when_to_use
When to Convert AAC to FLAC
- Converting AAC voice memos from iPhone to FLAC for archival in long-term personal recording libraries
- Preparing AAC tracks as FLAC masters for re-export at multiple bitrates without cumulative quality loss
- Migrating AAC podcast episode masters to FLAC for stable archival before mastering in iZotope RX
- Converting AAC sound effect libraries to FLAC for use in DAW projects with no further generational loss
- Archiving AAC field recordings as FLAC for inclusion in research datasets requiring lossless audio
//comparison
AAC vs FLAC
| Property | AAC | FLAC |
|---|---|---|
| Compression | AAC MDCT (lossy) | FLAC LPC (lossless) |
| Typical file size (4 min) | ~5 MB | ~25 MB |
| Generational loss | Cumulative on re-encode | None ever |
| Royalty-free | No (patent pool) | Yes (fully open) |
| iOS support | Native (preferred) | iOS 11+ (Files, Apple Music) |
| Best for | Streaming, distribution | Archival, mastering |
//how_it_works
How It Works
Drop your AAC files
Drag and drop or select AAC or M4A files at any bitrate. First use loads FFmpeg WASM (~30MB).
FFmpeg decodes AAC
FFmpeg WASM parses the ADTS or M4A container and decodes the AAC stream to raw PCM samples at the source sample rate.
FLAC encoding (lossless)
PCM is encoded with the native FFmpeg FLAC encoder at compression level 5, using linear prediction and Rice coding for lossless output.
Download your FLAC files
Your FLACs are ready for archival, DAW workflows, or playback on FLAC-compatible devices and apps.
// under the hood
AAC uses MDCT with temporal noise shaping (TNS) and perceptual noise substitution (PNS) for lossy compression. FLAC uses linear prediction with Rice coding for lossless compression of PCM. Our converter uses FFmpeg WASM to decode the AAC stream from the ADTS or M4A container to raw PCM, then re-encodes with the native FFmpeg FLAC encoder at compression level 5 (default). Output is bit-perfect to the decoded PCM.
//faq
Frequently Asked Questions
- Does FLAC restore the original AAC quality?
- No. FLAC cannot recover information lost during the original AAC encoding — AAC discards inaudible data permanently. Converting to FLAC gives you a perfectly preserved decode of the lossy AAC, but the AAC quality is the ceiling. FLAC prevents further loss, it doesn't restore past loss.
- Why convert AAC to FLAC then?
- Use FLAC when you plan to process the audio multiple times — re-export at different bitrates, run mastering passes, or archive long-term. Each AAC re-encode adds artefacts. Decoding once to FLAC and working from FLAC eliminates all further generational loss.
- What's the FLAC file size vs AAC?
- FLAC files are typically 3-6× larger than the source AAC, since FLAC stores the full PCM losslessly while AAC threw away most of it. A 4-minute AAC (~5 MB) becomes a ~25 MB FLAC. This is normal — it's the price of locking in a stable master.
- Will the FLAC play on iOS?
- FLAC is supported on iOS 11+ via the Files app and Apple Music import workflow. It's not as natively integrated as AAC on Apple devices, but it works. For broadest Apple compatibility, keep the AAC source for playback and use FLAC only for archival/editing.
- Are my AAC files private?
- Yes. FFmpeg WebAssembly runs entirely in your browser. Your AAC files never leave your device.
//related_converters
Related Converters
Similar conversions you might need.
Convert M4A to MP3
Convert Apple M4A audio files to universally compatible MP3.
→Convert AAC to MP3
Convert AAC audio files to widely compatible MP3 format.
→Convert AAC to WAV
Convert AAC audio to uncompressed WAV for editing in DAWs and audio tools.
→Convert AAC to OGG
Convert AAC audio to OGG Vorbis for open-source ecosystems and Linux compatibility.
→Convert MP3 to FLAC
Convert MP3 audio files to FLAC lossless format for archival and DAW workflows.
→Convert WAV to FLAC
Convert uncompressed WAV audio to FLAC lossless compressed format.
→