What Is FLAC? Lossless Audio Explained (2026)

The one-paragraph version

FLAC is to audio roughly what ZIP is to documents. It squeezes the file down and gives you every original bit back when you play it. That is the whole claim, and it is checkable rather than a matter of taste: decode a FLAC and the resulting PCM stream hashes identically to the WAV it came from. A 3-minute CD-quality track lands around 20–30 MB instead of 32 MB, and a 500-album collection runs comfortably past 150 GB.

Lossless, lossy, and why the distinction matters

Lossy formats — MP3, AAC, Ogg Vorbis — get small by throwing information away permanently, using models of what human hearing is unlikely to notice. A 320 kbps MP3 is a very good approximation. It is still an approximation, and re-encoding it degrades it again.

Lossless formats — FLAC, ALAC, WavPack, APE — get smaller by finding patterns, the way any general-purpose compressor does. Nothing is discarded, so converting between lossless formats is free of consequence and you can do it as many times as you like.

This is why FLAC is the format archives and CD rips use. It is not that FLAC sounds better than a good MP3 in a listening test — that argument is far less settled than the internet suggests. It is that a FLAC is a master copy. Anything else you might ever want can be produced from it; the reverse is not true.

Where FLAC fits on Apple devices

This is the part that catches people out, so it is worth being precise:

• iOS and macOS decode FLAC natively. They have since iOS 11. The operating system is not the problem.
• Apple's Music app still will not import it. The sync pipeline accepts ALAC, not FLAC. This is a product decision, not a technical limit, and it has not changed in years.
• The Files app will play a FLAC if you tap it. It gives you playback, not a library.
• AirPods do not receive lossless over Bluetooth. Bluetooth's bandwidth means AAC on the way to the earbuds regardless of the source file. Lossless matters over a wired DAC or on speakers; over AirPods, the file format stops mattering at the transmitter.

So "can my iPhone play FLAC?" is the wrong question — it can. The real question is which app is going to give you a library rather than a folder. Four working routes are laid out here.

FLAC or ALAC?

ALAC is Apple's lossless codec. Both decode to identical audio; neither sounds better than the other, ever. Pick by ecosystem: ALAC if your listening runs through Apple's Music app and its sync, FLAC for everything else, since it is what the rest of the world standardised on. Converting between them is lossless, so this is a reversible decision — the longer comparison is here.

Things people get wrong about FLAC

"FLAC is hi-res." It is not, by itself. FLAC is a container and a compression scheme; it will happily hold a 44.1 kHz/16-bit CD rip or a 192 kHz/24-bit studio file. The format tells you nothing about the resolution inside it.

"Higher compression level means lower quality." FLAC's compression levels (0–8) trade encoding time against file size. Every level is lossless. Level 8 takes longer to encode and produces a slightly smaller file that decodes to exactly the same audio as level 0.

"A FLAC download is guaranteed lossless." It is guaranteed to be a FLAC. If someone encoded a 128 kbps MP3 into FLAC, you get a large file containing the damage already done. This is common enough on the grey market to have its own diagnostic: a spectrogram of a genuine lossless file has content up to the Nyquist limit, while an upconverted lossy file shows a hard shelf where the encoder cut everything off.

Playing FLAC in Trove

Trove decodes FLAC natively on iPhone, iPad, Mac and Apple Watch — no conversion step, no import into another app's library, gapless between tracks, and tags, artwork and lyrics read straight out of the file. That part is free. If your FLAC library lives on a NAS rather than on the device, connecting over WebDAV or SMB is part of the one-time $9.99 unlock.

Related terms

• DSD — the other audiophile format, and a genuinely different technology
• Gapless playback — why live and classical albums need it
• WebDAV — reaching a FLAC library that does not fit on a phone