FLAC file format
FLAC compresses audio without losing a single bit: roughly half the size of WAV, mathematically identical to the original when decoded.
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What is FLAC?
FLAC (Free Lossless Audio Codec) was released in 2001 by Josh Coalson and later adopted by the Xiph.Org Foundation. Unlike MP3 or AAC, it throws nothing away. It predicts each sample from the ones before it and stores only the small prediction error, the same principle that makes ZIP work — applied to audio, and reversed perfectly on playback.
Typical music compresses to 50-60% of its WAV size. That is much worse than MP3, which reaches 10%, and much better than nothing at all when the goal is an archive you never have to redo. FLAC also fixed WAV's practical failings: it has a proper tagging system with artist, album, track and embedded cover art, and it stores a checksum so a corrupted file can be detected.
It is the standard for CD ripping, Bandcamp and hi-res download stores, and open-source music software. The historical gap was Apple, which pushed its own lossless codec ALAC and only added FLAC support to iOS in recent years. For everyday listening on phones, a lossy file is still smaller and indistinguishable to most ears.
| Extension | .flac |
|---|---|
| Category | Audio |
| MIME type | audio/flac |
| Released | 2001 |
| Developed by | Xiph.Org Foundation |
| Compression | Lossless |
FLAC: frequently asked questions
- Is FLAC really lossless?
- Yes, provably. Decoding a FLAC gives back a bit-for-bit identical copy of the original WAV — you can verify it by comparing checksums. The compression is reversible in the same way ZIP is; nothing about the waveform is approximated or discarded.
- FLAC or WAV — which should I keep?
- FLAC. The audio is identical, the file is 40-50% smaller, tags and cover art work properly, and a built-in checksum lets you detect corruption. WAV is worth keeping only as a working file inside an editor that demands it.
- Will I actually hear the difference between FLAC and MP3?
- On a 320 kbps MP3 through typical headphones, most listeners cannot in a blind test. The case for FLAC is not everyday listening — it is archiving: a lossless master can be re-encoded to any future format without stacking generation loss.
- What do the FLAC compression levels mean?
- Levels 0 to 8 control how hard the encoder works to find a smaller representation. The audio is identical at every level; only file size and encoding time change, and the spread between level 0 and 8 is just a few percent. Level 5 is the usual default.
- Do iPhones and Apple devices play FLAC?
- Modern iOS versions play FLAC through the Files app and many third-party players, though Apple's own ecosystem is built around ALAC, its equivalent lossless codec. If you live in Apple Music, ALAC integrates more smoothly; the audio quality is the same.
- Is there any point converting MP3 to FLAC?
- None for quality. The data an MP3 encoder discarded cannot be recovered, so you get a much larger file containing the same degraded audio. Do it only when a specific device or program refuses to read MP3 and insists on a lossless input.