Convert AAC to FLAC
To convert AAC to FLAC, add your .aac file below and press the button: it's processed on your own device and you download the result, with nothing uploaded. It's free, needs no account, and works with files up to 500MB.
About converting AAC to FLAC
AAC (.aac) files can be converted to FLAC entirely in your browser — no software to install, no file upload, and no account required. The conversion runs on a WebAssembly build of ffmpeg directly on your device.
Technical comparison
| AAC | FLAC | |
|---|---|---|
| Category | audio | audio |
| Compression type | Lossy | Lossless |
| Typical file size | Small — comparable to or smaller than MP3 at a given bitrate | Moderate — roughly 50–60% the size of the equivalent WAV |
| Transparency support | N/A (audio) | N/A (audio) |
How to convert AAC to FLAC privately
Every step below runs on a WebAssembly build of ffmpeg inside this browser tab. Your .aac file is never uploaded to a server — there's no network request carrying it anywhere.
Add your AAC file
Drag and drop, or click to select, a file (.aac). It's read straight from disk into browser memory — no upload step exists.
Convert locally
FreePrivateConvert converts it to FLAC using a WebAssembly build of ffmpeg, entirely within this browser tab.
Download the result
Save your converted .flac file. It only ever existed in this tab's memory — closing the tab without downloading discards it completely.
Convert AAC to FLAC with ffmpeg (command line)
Prefer the terminal? This is the exact ffmpeg command this page runs for you:
ffmpeg -i input.aac -c:a flac output.flac- -i input.aac
- Your AAC file.
- -c:a flac
- Encode the audio as FLAC (lossless: no quality is lost).
- output.flac
- The FLAC file to create. ffmpeg picks the container from this extension.
Don't have ffmpeg installed? You don't need it: use the converter at the top of this page. It runs the same conversion on your own device, and your file is never uploaded.
FAQ
- Is my file uploaded anywhere?
- No. Your file is read and processed inside this browser tab and never leaves your device. You can confirm it in your browser's developer tools: the Network tab shows no upload.
- Does converting AAC to FLAC reduce quality?
- FLAC is lossless, so nothing more is lost, but it can't restore what the AAC compression already removed. The file gets bigger without sounding better; it's only worth it if a tool requires FLAC.
- Is there a file size limit?
- Yes: 500MB per file. There's no account and no limit on how many files you convert.
- What's the difference between AAC and FLAC?
- AAC (Advanced Audio Coding) and FLAC (Free Lossless Audio Codec) store data differently. AAC: lossy. FLAC: lossless. FLAC is an open, lossless audio codec that compresses audio to roughly half the size of WAV with zero quality loss.
- Why convert AAC to FLAC?
- Common uses for FLAC: Audiophile music distribution and archival; Backing up CD rips without quality loss; Music production masters where lossless matters. Bit-perfect, mathematically lossless compression — decoded audio is identical to the original source, unlike MP3/AAC.
- What MIME type does a .flac file use?
- audio/flac, the standard type for Free Lossless Audio Codec.
- What is the ffmpeg command to convert AAC to FLAC?
- Run: ffmpeg -i input.aac -c:a flac output.flac. This is the exact command FreePrivateConvert runs for this conversion, so you can use this page instead of installing ffmpeg: it runs the same conversion inside your browser.
Learn more: What is a FLAC file
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