AAC to FLAC converter
Convert AAC to FLAC free online for tools that require lossless input. Wraps AAC audio in a FLAC container. FFmpeg engine, no signup, deleted in 1 hour.
Drop a file to convert here
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About Free Lossless Audio Codec
Common Use Cases
- Meeting FLAC input requirements from AAC sources
- Preparing Apple audio for lossless-only workflows
- Unifying a mixed-format library into FLAC
AAC is Apple's preferred lossy codec, and it delivers excellent quality at compact file sizes. But some audio tools, music servers, and upload platforms only accept lossless formats like FLAC. Converting AAC to FLAC wraps the decoded audio in a lossless container, which prevents any further quality loss and satisfies FLAC-only requirements. It is important to understand that this does not restore quality lost during the original AAC encoding; it preserves what remains in a lossless wrapper.
AAC is a lossy codec that discards audio data for compact files, while FLAC is a lossless container. Converting from AAC to FLAC preserves the remaining audio perfectly but cannot recover what AAC already discarded.
Why Convert AAC to FLAC?
Satisfy FLAC-only input requirements
Music servers, mastering tools, and some upload platforms require FLAC and reject other formats. If your source is AAC, converting to FLAC meets the format requirement and gets your audio into the pipeline.
Prevent further quality degradation
Once your AAC is in a FLAC container, every subsequent edit, trim, or re-export is lossless. This avoids the cumulative quality loss that happens when you repeatedly re-encode through lossy codecs.
Unify a mixed-format library
If your music collection is a mix of FLAC, WAV, MP3, and AAC, converting everything to FLAC gives you one consistent format that most modern players, servers, and library managers handle cleanly.
Better tagging and metadata
FLAC supports rich Vorbis comments with embedded cover art, lyrics, and detailed fields. Converting from AAC brings your metadata along and places it in a format that is well-supported across audiophile and general-purpose music players.
When to use each
Keep AAC when...
- Listening on iPhones, iPads, or Apple devices
- File size matters and quality is already acceptable
- Streaming within the Apple ecosystem
- Sharing compact files where AAC is supported
- Storage is limited and quality trade-offs are fine
Convert to FLAC when...
- A tool or platform requires FLAC input
- You need to edit audio without further loss
- Building a uniform FLAC music library
- Feeding audio into lossless-only mastering chains
- Archiving decoded audio for long-term preservation
Common use cases
- Meeting FLAC input requirements from AAC sources
- Preparing Apple audio for lossless-only workflows
- Unifying a mixed-format library into FLAC
How to use
- Upload your AAC file. Drag and drop your AAC file onto the upload area above, or click to browse your device. Uploads are capped at 500 MB per file.
- Start the conversion. Click the Convert File button. Your AAC is decoded to raw PCM audio and then losslessly compressed into FLAC on our servers using FFmpeg.
- Download your FLAC file. Once conversion finishes, a download link appears. Save the FLAC wherever you need it. Both your upload and the output are automatically deleted from our servers within 1 hour.
Frequently asked questions
- Does converting AAC to FLAC improve quality?
- No. AAC is lossy, so audio detail discarded during the original encoding cannot be recovered. The FLAC wraps the decoded audio in a lossless container, preserving exactly what was in the AAC without any further loss.
- Why is the FLAC file so much bigger than the AAC?
- AAC uses lossy compression that throws away data to achieve small file sizes. FLAC stores every decoded sample losslessly, which requires significantly more space. A 4 MB AAC file might become 15 to 25 MB as FLAC.
- Is converting AAC to FLAC free?
- Yes. Anyone can convert for free with no signup. Anonymous users get a daily conversion allowance, free registered accounts get a higher cap, and Premium or Lifetime members enjoy unlimited conversions.
- Will my metadata and cover art be preserved?
- Yes. Common metadata fields like title, artist, album, and track number are translated into FLAC Vorbis comments, and embedded cover art is carried across during conversion.
- How long are my files kept on your servers?
- Both your uploaded AAC and the converted FLAC are automatically deleted within 1 hour. All transfers are encrypted and files are never shared with third parties.