AAC vs FLAC
Which should you use?
Quick verdict
Use AAC for small files, streaming and mobile where wide compatibility matters; use FLAC for lossless archiving and high-fidelity libraries where bit-perfect quality matters more than file size.
AAC and FLAC solve different problems. AAC is a lossy codec that discards inaudible detail to produce small files, making it the default for streaming services, phones, and most consumer devices. FLAC is a lossless codec that compresses audio with no quality loss, so a decoded FLAC file is bit-identical to the original.
The trade-off is size versus fidelity. AAC files are a fraction of the size but cannot be restored to the original signal. FLAC files run about 50-60% of WAV size and preserve every sample, but they are larger and less universally supported on phones and streaming platforms.
At a glance
| Property | AAC | FLAC |
|---|---|---|
| Compression type | Lossy | Lossless |
| File size | Smallest | ~50-60% of WAV |
| Audio quality | Very good, not bit-perfect | Bit-perfect |
| Device support | Near-universal | Limited on phones/streaming |
| Best for | Streaming, mobile | Archiving, audiophile |
| Re-encoding loss | Loses quality each time | No loss |
Choose AAC when
- Choose AAC when you need small files for streaming or mobile
- Choose AAC when wide device and platform compatibility matters
- Choose AAC when storage or bandwidth is limited
- Choose AAC for everyday listening where the difference is inaudible
Choose FLAC when
- Choose FLAC when you want a bit-perfect, lossless archive
- Choose FLAC for a high-fidelity or audiophile music library
- Choose FLAC when you may re-encode to other formats later
- Choose FLAC when storage space is not a concern