AAC to FLAC Converter

What happens when you convert AAC to FLAC

• The audio is decoded and written as FLAC at compression level 5.
• FLAC is lossless, but it cannot restore what the AAC encoder already discarded. The FLAC will sound identical to the AAC and be several times larger.

How to convert AAC to FLAC online

1. Press "Choose AAC files" and select one or more files, or drag them onto the box. You can add files of any size your device can hold in memory.
2. Adjust the settings if you need to: the bitrate controls quality and size. The defaults suit most people.
3. Press "Convert to FLAC". The first audio or video conversion downloads the converter engine, about 32 MB, which your browser then keeps for next time.
4. Save each FLAC with its download button. Close the tab and every trace of the files is gone from memory.

Why convert AAC to FLAC?

AAC files usually come from iTunes and Apple Music, YouTube audio and streaming. People convert them to FLAC because FLAC keeps every detail of the original while cutting the size roughly in half compared with WAV.

In short, AAC is good at what it was made for, and FLAC is the more practical choice when the file has to play on another device or app. AAC plays in all current browsers and on Apple and Android devices, while FLAC plays in current browsers and most Android devices; iPhones play it in the Files app.

How to convert AAC to FLAC on Windows, Mac, iPhone and Android

On Windows

Open this page in Chrome, Edge or Firefox, drag your AAC files in from File Explorer, and press Convert. Each FLAC is saved to your Downloads folder. If you prefer a desktop program, VLC can also convert AAC to FLAC: choose Media, then Convert / Save.

On a Mac

Safari, Chrome and Firefox all work. Drag the AAC files from Finder onto the drop zone and the FLAC files land in Downloads.

On iPhone and iPad

Open the page in Safari and tap Choose AAC files. You can pick from Photos or from the Files app. The converted FLAC appears in Files, in the Downloads folder.

On Android

Open the page in Chrome, tap Choose AAC files and pick them from Files or your gallery. The FLAC is saved to the Download folder, where any file manager can find it. Keep the screen on while a long video converts, because Android may pause a tab in the background.

Best settings for AAC to FLAC

FLAC is lossless, so there is no quality setting: every sample of the decoded AAC is kept. What changes is size. CD-quality stereo, 44.1 kHz at 16 bits, takes about 10 MB per minute as uncompressed PCM, and roughly half to two thirds of that once compressed losslessly.

Since the AAC was lossy, the FLAC will sound identical to it, not better. Convert to FLAC when a program requires it, not to improve quality.

AAC vs FLAC: the differences

About AAC and FLAC files

What is an AAC file?

AAC was designed as the successor to MP3 and sounds better at the same bitrate, especially below 128 kbps. A bare .aac file is a raw stream with no chapters or cover art; the same audio in a container is usually called M4A.

What is a FLAC file?

FLAC shrinks audio to about half to two thirds of WAV size without losing a single sample, so it can be decoded back to a bit-identical copy of the original.

AAC to FLAC not working? Common problems

• The conversion is slow. Audio and container changes take seconds, but re-encoding video runs on your own processor. Lower the resolution to 720p, close other tabs, and keep the device plugged in.
• The tab stops or reloads on a very large file. Browsers limit how much memory one tab can use, around 2 GB and less on phones. Split long recordings or convert them on a computer.
• Song titles are missing. Tags such as title and artist are copied when FLAC can store them, but cover art is not carried over.

Convert AAC to FLAC with ffmpeg

This converter runs ffmpeg inside your browser. If you would rather use the ffmpeg command line on your own computer, this command produces an equivalent FLAC with the same kind of settings:

ffmpeg -i input.aac -vn -c:a flac output.flac

Replace input.aac with the name of your file. For a whole folder of AAC files, run the command in a loop, or drop them all on the converter above, which processes them one after another.