FLAC File Format (.flac)

A FLAC file holds audio compressed with the Free Lossless Audio Codec, which shrinks the data by roughly 40-60% and reconstructs the exact original samples, bit for bit, on decode.

.flacAudio Files

FLAC at a glance#

Full name	Free Lossless Audio Codec
File extension	.flac
Category	Audio Files
Developer	Xiph.Org Foundation
First released	2001
MIME types	audio/flacaudio/x-flac
Compression	Lossless
Specification	RFC 9639 (Free Lossless Audio Codec)
FileFlip support	FileFlip reads and writes this format

What a .flac file can hold#

These are the things a FLAC file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.

Lossless compression	Yes
Embedded metadata	Yes
Audio	Yes

Strengths and limitations of FLAC#

What FLAC does well

Decodes back to audio that is bit-for-bit identical to the source, with nothing discarded at any point
Typically 40-60% smaller than the uncompressed WAV or AIFF it was encoded from
Open and royalty-free, with no licensing fees for encoders, decoders or the format itself
Vorbis comment metadata blocks carry tags, cover art and ReplayGain loudness data inside the file

Where FLAC falls short

Still 2-3x larger than a comparable lossy MP3 or AAC file, since it can't discard any audio data
The Music app on macOS only gained native FLAC playback in macOS 10.13 (2017), and Windows Media Player in Windows 10
iOS supports FLAC playback since iOS 11, but decoding is hardware-dependent on older devices
Gains over lossy formats are inaudible on typical earbuds and phone speakers, so the benefit is mostly for archiving and editing

Use FLAC to archive or edit audio when you want compression without giving up any of the source quality.

Convert FLAC to MP3 or AAC for a portable device or streaming use case where storage space matters more than keeping a bit-perfect copy.

How to open a .flac file#

A .flac file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts FLAC into a format your machine already opens, and it does it in the browser tab rather than on a server.

Platform	Programs that open it
Windows	Windows Media Player, VLC, foobar2000
macOS	Music, VLC, Audacity
Linux	VLC, Audacious, Rhythmbox
iOS	Music, VLC
Android	VLC, the built-in media player
Web	FileFlip

FLAC questions people ask#

Does converting MP3 to FLAC improve the sound quality?

No, converting MP3 to FLAC does not improve sound quality. FLAC only guarantees that what goes into the encoder comes back out unchanged; it can't restore audio detail an MP3 encoder already discarded, so the result is a larger file that sounds exactly like the MP3 it came from.

Is FLAC actually lossless?

Yes, FLAC is genuinely lossless: decoding a FLAC file reproduces the exact same digital samples that went into the encoder, bit for bit, unlike lossy formats such as MP3 or AAC that permanently discard data. The compression works by predicting each sample from the ones around it and storing only the much smaller difference.

What plays FLAC files?

VLC, foobar2000 and Audacity play FLAC on any platform, and it's natively supported by Windows Media Player since Windows 10, by the Music app on macOS since 10.13 High Sierra, and by Android's built-in player since Android 3.1. Apple's Music app on iOS has played FLAC since iOS 11.

Can you hear the difference between FLAC and a high-bitrate MP3?

For most listeners on typical equipment, no: a 320 kbps MP3 and its FLAC source are very difficult to tell apart in a blind test. FLAC's advantage isn't sounding better, it's being an exact copy, which matters for archiving, editing or any further encoding step where compounding lossy artifacts is a real risk.

Does FLAC support surround sound and high-resolution audio?

Yes, FLAC supports up to 8 channels, bit depths up to 32-bit and sample rates up to 1,048,575 Hz, well beyond what a CD or a standard streaming file needs. That headroom is one reason it's the format record labels and archives use for high-resolution reissues.

Converting FLAC files#

Convert FLAC to another format

Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.