What is FLAC?
FLAC (Free Lossless Audio Codec) is an audio format that compresses audio files without discarding any data. The decompressed audio is bit-for-bit identical to the original source.
Created in 2001 by Josh Coalson as a free, open-source alternative to proprietary lossless formats like Apple's ALAC, FLAC has become the standard for audiophiles, music archivists, and anyone who needs to preserve audio quality while saving disk space compared to uncompressed WAV.
How Lossless Compression Works
FLAC uses a combination of prediction and residual coding:
- Prediction: the codec predicts each audio sample based on previous samples.
- Residual: only the difference between the prediction and actual value is stored.
- Entropy coding: the residuals are further compressed with Golomb-Rice coding.
Result: a FLAC file is typically 50-60% of the uncompressed WAV size, with zero data loss.
FLAC vs MP3 vs WAV
| Feature | FLAC | MP3 (320 kbps) | WAV |
|---|---|---|---|
| Compression | Lossless | Lossy | None |
| Quality | Identical to source | Very good | Identical to source |
| File size (1 min) | 4-6 MB | 2.5 MB | 10 MB |
| Metadata support | Full (Vorbis comments) | ID3 tags | Limited |
| Album art | ✅ | ✅ | Limited |
| Open source | ✅ | Patent expired (2017) | ✅ |
| Streaming support | Limited | Universal | Limited |
Does FLAC Sound Better Than MP3?
Technically, FLAC is identical to the source and MP3 is not. But in practice:
- Double-blind listening tests show most people cannot reliably distinguish FLAC from MP3 at 320 kbps.
- At 192 kbps, trained listeners can sometimes detect a difference in complex musical passages.
- At 128 kbps, differences are often audible.
The practical conclusion: FLAC is worth it for archiving and editing. For casual listening on earbuds, a well-encoded MP3 at 256-320 kbps is effectively transparent for most people and most audio systems.
When FLAC is Worth Using
Archive your music collection: FLAC is the gold standard for music archiving. You preserve every bit of your CDs or high-resolution downloads, and can always transcode to MP3 for smaller devices later. You cannot go the other way — once you discard audio data by encoding to MP3, you can't recover it.
High-end audio playback: if you have a quality DAC (Digital-to-Analog Converter), amplifier, and headphones or speakers, the uncompressed audio chain can reveal detail that compressed formats obscure.
Professional audio work: editing, mastering, and mixing should always use lossless formats. Every lossy encode/decode cycle adds noise.
Future-proofing: audio processing algorithms improve. Having the lossless original means you can re-process it with better tools in the future.
FLAC Compatibility in 2024
Software players: VLC, foobar2000, Winamp, MusicBee, Clementine, all Linux audio players — all support FLAC natively.
Hardware:
- Android: native support in the Files app and most music apps.
- iPhone/iOS: does NOT support FLAC natively. Use VLC for iOS, foobar2000 Mobile, or convert to ALAC.
- macOS: does NOT support FLAC in the Music app. Use foobar2000 for Mac, VLC, or convert to ALAC.
- Streaming services: Spotify, Apple Music, and Tidal use proprietary formats. Tidal "HiFi" streams FLAC at CD quality (16-bit/44.1kHz).
FLAC vs ALAC (Apple Lossless)
ALAC (Apple Lossless Audio Codec) is Apple's lossless format with identical audio quality to FLAC:
| FLAC | ALAC | |
|---|---|---|
| Quality | Identical | Identical |
| File size | Identical | Identical |
| Apple device support | Poor | Native |
| Everything else | Excellent | Poor |
Rule: use FLAC for everything except Apple ecosystem, where ALAC is the practical choice.
Converting FLAC Files
- FLAC to MP3 — for wide compatibility
- FLAC to AAC — for Apple devices
- FLAC to ALAC — lossless, Apple-native
- FLAC to WAV — for DAWs and professional use
- MP3 to FLAC — note: quality doesn't improve, MP3 data is fixed
Important Note: MP3 to FLAC
Converting an MP3 to FLAC does not improve audio quality. You get a lossless copy of an already-lossy file — larger, but not better. The only valid reason to do this is as an intermediate step in a processing workflow where subsequent tools require a lossless format.