Key takeaways
- Size = sample rate × bit depth ÷ 8 × channels × seconds: 30.3 MB for three minutes of CD audio.
- Checked on real files: 10 seconds of 48 kHz, 16-bit stereo is 1.92 MB by the formula and 1.92 MB as a WAV file (+0.06%, the header and metadata), 1.92 MB as AIFF, and 1.63 MB as FLAC (85% of the WAV).
Why uncompressed audio is big
Uncompressed audio stores every sample: the sample rate times the bit depth times the channels. CD audio is 44,100 samples a second, 16 bits each, two channels, which is 1,411 kbps.
Compression formats trade size for effort: lossless ones such as FLAC give the same samples back in less space, lossy ones such as MP3 do not.
Scenarios
| Scenario | Uncompressed size | Data rate | Per minute |
|---|---|---|---|
| CD audio, 3 minutes | 30.3 MB | 1411 kbps | 10.1 MB |
| 48 kHz 16-bit stereo, 10 minutes | 109.9 MB | 1536 kbps | 11.0 MB |
| 48 kHz 24-bit stereo, 10 minutes | 164.8 MB | 2304 kbps | 16.5 MB |
| 96 kHz 24-bit stereo, 1 hour | 1.93 GB | 4608 kbps | 33.0 MB |
| 44.1 kHz 16-bit mono, 1 hour | 302.8 MB | 706 kbps | 5.0 MB |
Measured: one excerpt in three uncompressed or lossless formats
| Format | Size | Against the formula |
|---|---|---|
| Formula (48 kHz, 16-bit, stereo, 10 s) | 1.92 MB | 0.0% |
| WAV | 1.92 MB | +0.06% |
| AIFF | 1.92 MB | +0.06% |
| FLAC (lossless compression) | 1.63 MB | -15.2% |