What is the FLAC file format?
There are many audio codecs available on the internet, but .flac stands out among them for quality. Like .MP3, it is a compressed audio format - but the key difference is that .flac does not lose any of the qualities of the original audio. This is what makes it a lossless codec: compression reduces file size to roughly 50-60% of an equivalent .WAV without discarding a single sample.
.flac was developed by Josh Coalson and released in 2001, now maintained by the Xiph.Org Foundation as a fully open, royalty-free standard, formally codified as IETF RFC 9639 in December 2024. Native .flac files start with the four-byte ASCII marker fLaC at file offset 0; the audio stream can also be carried inside an .OGG container.
You can open .flac files on any device or application that supports the format, and support is now very broad - covering desktop players, mobile apps, and dedicated audio tools. This is truly one of the most widely used lossless codecs: you can trust the quality because what you decode is bit-for-bit identical to the original recording.
Security & safety
RISK: LOWA .flac file is plain audio data with no executable code, so the format itself is safe. Usual caveats only: keep your media player updated (malformed media can target player bugs), and don't upload personal recordings to untrusted online converters. Beware random "FLAC player/converter" downloads from ad-heavy sites - stick to VLC, foobar2000, AIMP, fre:ac or the official Xiph tools.
Format details
in a nutshellPrograms that open FLAC files
Windows4 apps
VLC media player
Open-source Drag the .flac onto VLC - plays out of the box, including hi-res files. 
Windows Media Player / Media Player
Built-in Windows 10/11 play FLAC natively since 2017 - double-click to play. 
macOS2 apps
VLC media player
Open-source Plays FLAC directly. Apple Music/QuickTime historically didn't (Apple prefers ALAC). 
Linux2 apps
VLC media player
Open-source Plays FLAC; virtually every Linux player (Rhythmbox, mpv, Audacious) supports it.
flac (reference tools)
Open-source Command line: 'flac -d file.flac' decodes to WAV; 'flac file.wav' encodes. The reference codec. 
Android1 app
VLC for Android
Open-source Open the .flac from the Audio tab; Android 8+ also plays FLAC in many stock players.
VLC for iOS
Open-source Share/Open the .flac in VLC. iOS plays FLAC in the Files app since iOS 11, but not in Apple Music. Technical details
deep spec| Compression type | Lossless - decoded audio is bit-for-bit identical to the source PCM |
| Typical size reduction | Roughly 40-60% smaller than equivalent uncompressed audio, depending on content |
| Magic bytes | `fLaC` (hex 66 4C 61 43) at file offset 0, immediately followed by the STREAMINFO metadata block |
| MIME type | `audio/flac` |
| Supported bit depths | 4 to 32 bits per sample |
| Supported sample rates | 1 Hz to 655,350 Hz |
| Maximum channels | Up to 8 channels (sufficient for 7.1 surround audio) |
| Container options | Native `.flac` stream or embedded in an Ogg container (`.oga` extension) |
| Metadata format | Vorbis comment tags; embedded cover art stored in a PICTURE metadata block |
| Seek support | Random-access seeking via an optional SEEKTABLE block stored in the file header |
| Error detection | MD5 checksum of raw audio in STREAMINFO; per-frame CRC-8 (header) and CRC-16 (footer) checksums |
| Encoding algorithm | Linear predictive coding (LPC) for signal modelling; Rice entropy coding for residuals |
| Formal standard | IETF RFC 9639 (published December 2024) |
| Patent and royalty status | Royalty-free; no software patents claimed on the format or codec |
| Streaming | Supports HTTP progressive streaming and byte-range delivery in native stream form |
| Released | 2001 (1.0); formally specified as IETF RFC 9639 in December 2024 |
| Open standard | Yes · royalty-free |
| Specification | datatracker.ietf.org |
FLAC conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about FLAC files.
