FLAC vs ALAC: Which Lossless Audio Format Should You Use

FLAC and ALAC are both lossless audio formats, and they sound exactly the same: decode either one and you get back a bit-for-bit copy of the original PCM audio. The real FLAC vs ALAC decision comes down to ecosystem and file size. FLAC compresses a few percent smaller and runs on nearly everything except Apple's own Music app, while ALAC (Apple Lossless) is the format iTunes, Apple Music, and iPhones handle natively.

So the short version: use FLAC unless your library lives inside Apple's Music app, in which case use ALAC. Below is the detail behind that call, including compression numbers, metadata differences, and why FLAC is the safer choice for long-term audio archiving.

FLAC vs ALAC at a glance

Does FLAC or ALAC sound better?

Neither. This is the part people get wrong most often, so it's worth being blunt about it: when you ask about FLAC vs ALAC quality, the answer is that both are mathematically lossless. Encode a 24-bit/96 kHz master to FLAC, decode it, and you get the identical sample values you started with. Do the same with ALAC and you get the same identical samples.

Lossless compression works like a ZIP file for audio. It finds patterns in the waveform, stores them more efficiently, and reconstructs the original perfectly on playback. Nothing is thrown away, unlike lossy codecs such as MP3, AAC, or Opus (see Opus and AAC at low bitrates), which permanently discard audio data your ears are unlikely to notice.

File size and compression differences

FLAC compression is generally a bit more efficient than ALAC. On typical pop or rock material at 16-bit/44.1 kHz, FLAC at its default setting lands around 55-60% of the original WAV size, and ALAC usually ends up 1-4% larger on the same track. On a 500 GB library, that's roughly 5-20 GB of difference, not a deal breaker.

FLAC also gives you compression levels 0 through 8. Level 0 encodes fastest and compresses least, level 8 squeezes hardest and takes noticeably longer. Level 5 is the default and sits in a sensible spot.

# same audio, three effort levels
flac -0 track.wav -o fast.flac     # fastest encode, largest file
flac -5 track.wav -o default.flac  # the standard balance
flac -8 track.wav -o small.flac    # slowest encode, ~2-3% smaller

The jump from level 5 to level 8 usually buys you only around 1% extra savings for several times the encode time. Decoding speed is unaffected by the level, so there's no playback penalty either way.

ALAC has no user-facing compression levels. You get one setting, and encoders just do their thing. If you want the full picture on how uncompressed audio balloons in the first place, the breakdown of why WAV files are so huge explains where all those megabytes come from.

Real-world numbers on a 4-minute track

• WAV (16-bit/44.1 kHz stereo): about 42 MB
• FLAC level 5: about 24-26 MB
• ALAC: about 25-27 MB
• AAC 256 kbps (lossy): about 7.5 MB

Dense, loud, heavily limited material compresses worse in both formats. A quiet solo piano recording can drop below 40% of WAV size; a wall-of-noise metal master might only reach 70%.

Device and app support

This is where FLAC vs ALAC actually gets decided for most people.

Where FLAC wins

• Android: native FLAC playback since Android 3.1
• Windows 10 and 11: built-in support, including File Explorer metadata
• Streaming services: Qobuz, Tidal, and Bandcamp all offer FLAC downloads or streams
• Hardware: most network streamers and virtually every dedicated digital audio player
• Software: VLC, foobar2000, Plex, Jellyfin, Roon, Audacity, and every DAW worth using

Where ALAC wins

• Apple Music app on macOS and iOS: imports and syncs ALAC; will not import FLAC into your library
• Apple Music lossless streaming: delivered as ALAC, up to 24-bit/192 kHz
• iPhone and iPad sync: ALAC files move across without conversion
• Apple Watch, HomePod, AirPlay 2: handled natively

The nuance people miss: iOS can play FLAC. Since iOS 11, the Files app and many third-party players (VLC, Foobar2000 Mobile) handle FLAC fine. What Apple still refuses to do is let FLAC into the Music app library, so it won't sit alongside the rest of your albums or sync through Apple's own pipeline.

Tags, album art, and metadata

FLAC uses Vorbis comments, a flexible key-value system where you can invent your own fields. That's great for classical collections that need conductor, orchestra, and catalogue number tags, and it handles multi-value fields (three artists on one track) cleanly. Album art goes into a dedicated PICTURE block.

ALAC inherits MP4 atom tagging, the same iTunes-style metadata used by AAC. It's more rigid and multi-value fields are handled awkwardly, but it maps perfectly onto what Apple's Music app expects, including sort fields, compilation flags, and gapless playback info.

Practical takeaway: if you have a large, unusually tagged collection, FLAC gives you more room. If your tags come from and go back to Apple Music, ALAC keeps everything intact.

Which format is better for audio archiving?

FLAC, and by a clear margin. Three reasons:

1. Built-in integrity checking. Every FLAC file stores an MD5 checksum of the decoded audio in its STREAMINFO block. Running flac -t on your library tells you instantly whether any file has bit-rotted or been corrupted during a drive migration. ALAC has no equivalent.
2. Open specification. FLAC was standardised by the IETF as RFC 9639 in 2024, which means there's a formal, permanent, vendor-neutral description of the format. ALAC's reference source is open, but it is not a standards-body specification.
3. Independence from one company. FLAC is maintained by Xiph.Org with no single commercial owner steering it. ALAC's direction is Apple's to decide.

Libraries, national archives, and CD-ripping communities have settled on FLAC for exactly these reasons. If you're ripping a CD collection you don't want to rip twice, archive to FLAC and generate ALAC copies for your iPhone from that archive.

Converting between FLAC and ALAC

Because both decode to identical PCM, converting FLAC to ALAC or back loses nothing. You can do it as many times as you like without any generational degradation, which is not true for lossy formats.

What you should watch for:

• Metadata drift. Vorbis comments and MP4 atoms don't map one to one. Custom tags may be dropped, so check a few files after a batch conversion.
• Album art resizing. Some converters re-encode embedded artwork. Cosmetic, but annoying if you had high-resolution covers.
• Sample rate must stay put. If your converter resamples 96 kHz down to 44.1 kHz, the result is no longer lossless relative to the source, regardless of the container.
• Bitrate settings are meaningless here. Lossless encoders compute their own output size from the audio, so a bitrate slider has no effect on FLAC output.
• Check the codec, not the extension. An .m4a can be lossless ALAC or lossy AAC, so a converter that offers M4A may be giving you AAC.

If you're curious how containers, codecs, and extensions relate to one another in general, the primer on what a codec actually is makes the distinction clear.

Which one should you actually use?

One last reality check: lossless only matters if the rest of the chain justifies it. On a phone with wireless earbuds, Bluetooth re-encodes everything to SBC, AAC, aptX, or LDAC anyway, so your ALAC file is being converted to a lossy stream before it reaches your ears. Lossless pays off for archiving, for wired listening, and for any file you might re-encode later.

Turn Your WAV Masters Into FLAC in Seconds

Once you've made the FLAC vs ALAC call, our free online audio converter can create the FLAC: drop in a WAV or other audio file, pick FLAC, and download the result. It also outputs MP3, WAV, M4A, AAC, OGG, WMA, AIFF and MP2. Note that M4A here means lossy AAC, not ALAC, so for Apple Lossless copies use a dedicated tool such as XLD, dBpoweramp or ffmpeg. No login, no software install.

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