ALAC vs AAC: Apple Lossless vs Lossy Audio Compared
Published on March 21, 2026
ALAC (Apple Lossless Audio Codec) keeps every bit of audio data from the original recording, producing files about half the size of the source WAV. AAC (Advanced Audio Coding) is a lossy codec that discards inaudible frequencies, resulting in files 80-90% smaller than the original. Both are Apple-native, but they serve different purposes: ALAC is for archival quality, AAC is for everyday listening.
Sound Quality
ALAC is bit-for-bit identical to the source. Decode an ALAC file and you get back exactly the same data as the original CD or master recording. AAC at 256kbps (the Apple Music default for purchases) sounds excellent and most listeners cannot distinguish it from lossless in blind tests. The quality gap only becomes noticeable on high-end equipment at lower AAC bitrates (below 128kbps) or with highly dynamic classical and jazz recordings.
File Size
A 4-minute song takes roughly 25MB as ALAC versus 8MB as AAC 256kbps. That is a 3:1 ratio. For a 1,000-song library, ALAC needs about 25GB while AAC fits in 8GB. On a 64GB phone where storage is shared with apps, photos, and videos, this difference is significant. ALAC still compresses well compared to uncompressed WAV (which would be 40MB+ per song), but AAC is far more storage-efficient.
Apple Ecosystem Support
Both formats work natively on iPhone, iPad, Mac, Apple TV, HomePod, and AirPods. Apple Music streams in ALAC for its Lossless tier and AAC for standard streaming. iTunes purchases use AAC 256kbps. If you rip CDs using Apple Music (formerly iTunes), you can choose either format. Outside Apple, AAC has broader support: Android, Windows, game consoles, and most car stereos handle AAC. ALAC plays on fewer non-Apple devices, though FLAC is the cross-platform alternative for lossless audio.
Streaming and Bandwidth
AAC at 256kbps uses about 2MB per minute of music, making it practical for cellular streaming. ALAC requires roughly 6MB per minute, which drains data plans quickly. Apple Music defaults to AAC on cellular connections and only streams ALAC on Wi-Fi (unless you override the setting). For podcast listening and casual music on the go, AAC is the practical choice.
When to Use Each
Use ALAC when building a permanent music library on a device with plenty of storage, when using high-end DACs or headphones where lossless quality matters, or when archiving CD collections. Use AAC for streaming, mobile listening, podcasts, and any situation where storage or bandwidth is limited. If you already have an AAC library, converting to ALAC will not improve quality since the data was already lost during the initial AAC encoding.
Need to adjust audio file sizes? Our audio compressor lets you convert between bitrates. For more audio format comparisons, see AAC vs OGG and Opus vs AAC.