Convert your .aac files to .flac format online for free. No software to install. Fast, secure, and easy.
Pro account required for audio & video
Drag and drop your .aac file or click to browse.
Select FLAC as your output format.
Click Convert and download your .flac file.
While converting AAC to FLAC will not recover audio data lost during the original compression, it creates a lossless container that prevents further degradation. This can be useful for archival or when your workflow requires lossless input files.
AAC (Advanced Audio Coding, introduced in 1997) uses Lossy (MDCT-based with TNS and PNS tools) compression. FLAC (Free Lossless Audio Codec, introduced in 2001) uses Lossless (linear prediction + Rice coding) compression. AAC browser support: Universal. FLAC browser support: All modern browsers (Chrome, Firefox, Edge; Safari 11+).
Converting from AAC (lossy) to FLAC (lossless) will not recover quality that was lost during the original AAC compression. The conversion preserves the current state of the file without further degradation. The resulting FLAC file will be larger than the AAC original.
Typical AAC file size: A 4-minute song at 256 kbps AAC-LC: ~7.3 MB. Typical FLAC file size: A 4-minute song at 44.1 kHz/16-bit: ~20-30 MB. The FLAC output will be larger than the AAC input because lossless compression cannot match the compression ratios of lossy formats.
FLAC compression level (0-8) only affects encoding speed and file size, not audio quality — all levels produce bit-identical audio. Level 5 is a good default balance. Levels 6-8 save marginal space at significantly slower encoding speeds.
Convert AAC to FLAC with 3 free conversions per day. No hidden fees.
Create a free account in 10 seconds and start converting immediately. No credit card required.
Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion.
Convert files from any device — desktop, tablet, or phone. No software to install, works in any modern browser.
SquishConvert supports over 358 file conversion combinations across images, documents, audio, and video.
Your converted .flac file maintains the best possible quality. No unnecessary compression or quality loss.
Audio conversion requires a Pro account. See pricing — starting at $4.99/month
You get 3 free conversions per day. Audio conversions require a Pro account.
Most files convert in under 10 seconds. Larger files may take a bit longer depending on size.
Yes. Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion. We never store your files.
Currently, SquishConvert converts one file at a time. Batch conversion is coming soon — stay tuned!
Free users can convert files up to 10 MB. Pro users can convert files up to 500 MB.