Does FLAC actually sound better than ALAC?

No. Both are mathematically lossless and decode to bit-identical PCM samples. The audio coming out of a FLAC decoder is byte-for-byte the same as the audio coming out of an ALAC decoder when both started from the same WAV source. You can verify this with any checksum tool. Any perceived sonic difference is psychological — the placebo effect is real, and people who believe one format sounds better than the other will hear differences in non-blind tests. In ABX double-blind testing, no listener has ever reliably distinguished FLAC from ALAC, because there is nothing to distinguish.

Can iPhone play FLAC files?

Yes. iOS 11 (2017) added native FLAC playback in the Files app and the system audio framework. FLAC files play correctly with no third-party app needed. The caveat is that FLAC files do not appear in the Music app library automatically — they live in Files. ALAC files, by contrast, integrate with the Music app and behave like first-class library entries. If you want lossless files that show up in your iOS Music library and Apple Music, ALAC is the simpler path. If you just want to play a FLAC occasionally from Files or AirDrop, iOS handles it natively.

Is ALAC the same as M4A?

Not exactly. M4A is a container, not a codec — the .m4a extension just signals 'audio-only MPEG-4'. The audio inside an M4A file can be either AAC (lossy) or ALAC (lossless). Most M4A files in the wild contain AAC (Voice Memos, iTunes Store purchases, Apple Music streaming up to 256 kbps). The lossless variant — used by Apple Music's Lossless tier and Apple's own ripping pipeline — contains ALAC. To check: open the file's properties in iTunes / Music, or run 'ffprobe' on the command line. The codec field will say 'AAC' or 'ALAC'.

Why does Apple Music use ALAC instead of FLAC?

Technical and ecosystem reasons, not quality. Apple's audio framework (Core Audio, AVFoundation) was built around ALAC long before FLAC was widely adopted. AirPlay 2 carries ALAC end-to-end, HomePod and Apple TV decode it natively without re-encoding, and the iTunes / Music app has 20 years of ALAC tooling. Switching to FLAC would require re-engineering parts of that stack with no audible benefit, since the two formats are functionally identical at the audio level. Apple has shown no roadmap toward FLAC adoption and there is no pressure for one — the ecosystem is fully committed to ALAC.

Will Windows play ALAC files natively?

Limited and not as cleanly as FLAC. Windows 10 and 11 play FLAC files natively in Media Player, File Explorer and Movies & TV. ALAC support is more patchy — Windows can decode ALAC inside an .m4a wrapper through the MP4 framework, but tools sometimes refuse to index ALAC libraries correctly. The clean Windows path for lossless audio is FLAC. If you are crossing between Mac and Windows regularly and want one format that works first-class on both, FLAC is the better choice. ALAC will play through VLC and foobar2000 on Windows but the native experience is weaker than FLAC.

Can I convert FLAC to ALAC without losing quality?

Yes, completely losslessly. Both formats store the same PCM samples in different wrappers, so converting between them is a decode-and-re-encode operation that produces bit-identical audio. Use [FLAC to M4A](/flac-to-m4a) to convert FLAC into ALAC inside an MP4 container — the output plays natively on iPhone, Mac and Apple Music. The audio data does not change. You can round-trip FLAC → ALAC → FLAC → ALAC indefinitely and the samples remain identical at every step. This is the test that distinguishes lossless from lossy formats: round-trip a lossy MP3 and the file changes every iteration; round-trip a lossless FLAC or ALAC and it stays the same forever.

Which compresses smaller, FLAC or ALAC?

FLAC, by a small margin. On real-world music content, FLAC produces files roughly 1-3% smaller than ALAC at default settings. The difference is bigger on sparse content (acoustic, voice) and smaller on dense content (modern loud-mastered pop). A typical 600 MB CD album lands around 280-320 MB as FLAC versus 290-330 MB as ALAC — meaningful only at library scale. Encode speed slightly favours ALAC on Apple silicon thanks to hardware acceleration; decode speed is essentially equivalent on modern CPUs. If you are choosing for compression efficiency alone, FLAC wins narrowly. If you are choosing for any other reason, the difference is too small to be a deciding factor.

FLAC vs. ALAC: Lossless Audio Format Comparison

FLAC and ALAC are the two lossless audio codecs most people actually encounter in the wild. They do the same job — preserve every PCM sample exactly — and they do it with very similar efficiency. The choice between them is almost never about audio quality. It is about which device ecosystem you live in, which apps will play the files without friction, and which format your future self will still be able to read in 20 years. This guide is the honest comparison for anyone deciding which lossless format to rip CDs to, archive a music library in, or download from Apple Music or Bandcamp.

Both Are Mathematically Lossless

The single most important point: FLAC and ALAC are both bit-perfect lossless. A WAV → FLAC → WAV round-trip produces a byte-identical WAV. A WAV → ALAC → WAV round-trip produces a byte-identical WAV. A FLAC → ALAC → FLAC round-trip is also byte-identical. The audio data is the same. There is no debate to be had about which sounds better, because they decode to the same PCM samples — you can verify with any checksum tool. Anyone claiming one is sonically superior to the other is wrong.

What this means in practice: choosing between them is a workflow and compatibility decision, not a quality decision.

What Each Format Actually Is

FLAC (Free Lossless Audio Codec) was released by Josh Coalson in 2001 and is now maintained by the Xiph.Org Foundation. It is open-source under a BSD-style license, patent-free, and royalty-free. The reference encoder/decoder is small, well-documented, and has been ported to every operating system. The .flac container is purpose-built — it stores the compressed audio, Vorbis Comment metadata, embedded album art and an MD5 checksum of the decoded PCM in a single file. See what is FLAC for the full background.

ALAC (Apple Lossless Audio Codec) was introduced by Apple in 2004 as a Mac OS X technology, originally proprietary. Apple open-sourced ALAC in 2011 under the Apache 2.0 license, which made it patent-clean and freely implementable. ALAC samples are stored inside an MP4 container — the same container that holds AAC for M4A files. The file extension is typically .m4a (Apple's preferred), occasionally .alac, and the container exposes the same metadata atoms used by AAC files (iTunes-style tags, embedded artwork, chapter markers).

Compression Efficiency

In real-world benchmarks the difference is small but consistent: FLAC compresses slightly better than ALAC — typically 1-3% smaller files at default settings on the same source material. On a 1 GB album, that is 10-30 MB difference. Neither codec compresses well on highly random content (white noise, very loud full-spectrum mixes); both compress well on sparse content (acoustic chamber music, voice).

A standard CD album (around 600 MB as WAV) typically lands around 280-320 MB as FLAC and 290-330 MB as ALAC. Not a meaningful difference for most users. If disk space is genuinely the constraint, FLAC wins by a hair, but the bigger driver of size is the source material itself.

Encode speed favours ALAC slightly on Apple silicon (it has hardware-accelerated decode in Apple's Core Audio framework). Decode speed is roughly equivalent on modern hardware — both decode dozens of streams in real time on a single CPU core.

Apple Ecosystem: ALAC Wins

If your listening environment is 100% Apple — iPhone, iPad, Mac, HomePod, Apple TV, Apple Watch, AirPods Max via lossless cable — ALAC is the friction-free choice:

iOS Music app plays ALAC natively. Lossless files appear in your library normally and play with no hiccups.
Apple Music's lossless tier delivers ALAC, not FLAC. If you are downloading from Apple Music for offline listening, the files are already ALAC and there is nothing to convert.
HomePod and HomePod mini play ALAC natively over AirPlay.
Apple TV plays ALAC.
macOS Music app, iTunes Match, and the legacy iTunes Store were all built around ALAC.

iOS has supported FLAC playback in the Files app since iOS 11 (2017), and ALAC since forever. Both work, but ALAC integrates more cleanly with the Music app and Apple Music — FLAC files in iOS land in Files but do not appear in your Music library by default.

Cross-Platform Listening: FLAC Wins

If your listening is mixed across platforms — Mac and Windows, iPhone and Android, Roon, Plex, Jellyfin, Squeezebox, foobar2000, MusicBee, VLC, a NAS, a car stereo with USB playback — FLAC is the pragmatic choice:

Windows 10 and 11 play FLAC natively in File Explorer and Media Player. ALAC requires a codec pack or third-party player.
Android supports FLAC natively from Android 3.1 onward. ALAC support is patchy and depends on the player app.
Linux supports FLAC natively in every major distribution and audio player.
DAWs: most modern DAWs read both. FLAC has marginally wider support in production tools.
Media servers (Plex, Jellyfin, Roon, Logitech Media Server) all index FLAC perfectly. Roon supports ALAC fully but most others are FLAC-first.
Hi-res download stores (HDtracks, Qobuz, ProStudioMasters, 7digital) deliver FLAC. Bandcamp's lossless tier delivers FLAC.
Discogs and music-trading communities standardise on FLAC.

If you ever want to share a lossless file with a friend, post-process it in software outside Apple's ecosystem, or hand it to a media server, FLAC has the higher hit rate.

Metadata: Different Systems, Both Work

Both formats handle metadata well, but in different ways:

FLAC uses Vorbis Comments — flexible key/value pairs with custom-field support and embedded album art via METADATA_BLOCK_PICTURE. Tools that read FLAC tags (foobar2000, MusicBee, Mp3tag, Picard, beets, kid3) preserve every field including custom ones.

ALAC uses iTunes-style MP4 atoms — the same metadata system as AAC files, with strong tag support for the standard fields (title, artist, album, genre, year, track number, disc number, composer) and embedded album art. iTunes / Apple Music writes and reads these reliably. Outside the Apple ecosystem, MP4 metadata support is universal but tools occasionally miss less common fields.

For a personal library: both work. FLAC's Vorbis Comments are slightly more extensible for custom workflows. ALAC's MP4 atoms are slightly better integrated with Apple Music.

File Integrity

This is FLAC's quietly important advantage. Every FLAC file embeds an MD5 hash of the decoded PCM in its STREAMINFO block. The 'flac --test' command verifies that hash against the actual decoded samples — if a single bit on disk has corrupted, the test fails and you know which file is damaged. ALAC has no equivalent built-in checksum, so silent disk corruption can rot an ALAC archive without warning unless you maintain external manifests (sha256sum, par2, BagIt).

For long-term archival on consumer storage where bit rot is a real risk, this is one of the strongest reasons to lean FLAC. See WAV vs FLAC for archiving for the full archival argument, which applies to ALAC vs FLAC the same way.

Apple Music's Choice and Why It Matters

Apple Music's lossless tier (launched 2021) delivers ALAC at up to 24-bit / 192 kHz. Apple chose ALAC for technical and ecosystem reasons — their decoder pipeline is built around it, AirPlay 2 carries ALAC end-to-end, and HomePod / Apple TV decode it natively without round-tripping. There is no roadmap or signal that Apple will adopt FLAC; the two codecs are functionally interchangeable from a quality perspective so there is no pressure to switch.

If you subscribe to Apple Music's Lossless tier and download for offline listening, you have ALAC files. If you ever want them in FLAC for use outside the Apple ecosystem, the conversion is lossless — see FLAC to M4A for the reverse direction (which is also lossless, audio data unchanged).

Conversion Between Them

FLAC ↔ ALAC conversion is completely lossless. Both decode to identical PCM, so going from one to the other is just decoding to PCM and re-encoding into the other format. Round-trip checksums match. There is no quality reason to avoid converting between them.

The practical paths:

FLAC → ALAC for Apple devices: convert via the FLAC to M4A converter. The output is ALAC inside an M4A container, native to iPhone, Mac, Apple Music import.
ALAC → FLAC for non-Apple use: also lossless. Most converters can do this directly, or via a WAV intermediate.
FLAC ↔ WAV for DAW work: /flac-to-wav and /wav-to-flac.

If you have a personal library and want to standardise, picking either format and converting everything is a one-time job — and the audio is identical at every step. See lossless vs lossy for why this matters.

The Practical Recommendation

100% Apple devices, you use Apple Music, you do not share lossless files with non-Apple users: ALAC. It plays everywhere natively in your environment with zero friction.
Mixed environment (Mac and Windows, iPhone and Android, NAS, media server): FLAC. Universal support, slightly better compression, built-in integrity verification.
Long-term personal music archive that needs to outlive any single platform: FLAC. The integrity checksum and the open, patent-free spec make it the more durable choice.
You buy lossless music from Bandcamp, HDtracks, Qobuz, or other download stores: they deliver FLAC. Keep your library in FLAC and convert specific files to ALAC for Apple Music import as needed.
You are an audiophile, listening on a high-end DAC, with a Mac mini as a dedicated music PC: either works. Most audiophile-focused players (Roon, Audirvana, JRiver) handle both equally well.

The audio is the same. Pick the one your ecosystem prefers and stop worrying about it.