Estimate storage for your music library.
Audio file size is bitrate times duration, and the format choice spans an eleven-fold range: 128 kbps MP3 against uncompressed WAV. Lossless FLAC lands around 900 kbps for typical material, roughly three times a high-quality MP3 — which is the trade-off that decides whether a four-thousand-track library fits on a phone or needs a dedicated drive.
Track size
MB per track = bitrate kbps x minutes x 60 / (8 x 1024)
Library size
Library GB = MB per track x tracks / 1024
It matters for archiving, since lossless files can be re-encoded to any future format without generational loss. For listening on ordinary equipment, most people cannot distinguish it from 256 kbps AAC.
It is lossless compression, so the rate depends on the music. Dense loud material compresses less and can exceed 1000 kbps, while sparse acoustic recordings drop well below 700.