.flac — Free Lossless Audio Codec
Audio audio/flac
What a .flac file is
Lossless audio compression — bit-for-bit identical to the source at roughly half the size of WAV.
How to open it
VLC, foobar2000, most modern players. Apple added support in 2017.
Worth knowing
Use it for archiving a CD collection. For listening on a phone, a high-bitrate lossy file is indistinguishable and far smaller.
How to identify a .flac file
A file's extension is only its name — renaming a.png to a.flac changes nothing inside. What software actually reads is the magic number, the first few bytes of the file.
| Signature | 66 4C 61 43 |
| MIME type | audio/flac |
| Category | Audio |
ASCII "fLaC".
# what is this file really?
file mystery.flac
# look at the first bytes yourself
xxd mystery.flac | head -2
head -c 16 mystery.flac | xxd
# Windows PowerShell
Get-Content mystery.flac -AsByteStream -TotalCount 16 | Format-HexFrequently asked questions
What is a .flac file?
Lossless audio compression — bit-for-bit identical to the source at roughly half the size of WAV.
How do I open a .flac file?
VLC, foobar2000, most modern players. Apple added support in 2017.
Is .flac safe to open?
Yes. A .flac file is data, not code — opening one cannot execute anything by itself.
Can I change a file's extension to convert it?
No. Renaming changes the label, not the bytes. The one place it appears to work is between formats that genuinely share a container — renaming .docx to .zip works because a DOCX is a ZIP. Everything else needs a real converter.