What it is Good For

The main usefulness of MP3 is that you can get a lot of music in a little space, and retain a relatively high level of fidelity. For a small reduction in quality it is possible to store a large number of files.

Beck's "Devil's Haircut" from his album Odelay is 3 minutes 14 seconds long and takes 32.6 MB of space as an AIFF file. At the usual bit rate of 160 kbps, an MP3 of "Devil's Haircut" takes up 3.8 MB (encoded with iTunes 4.6). That means you save 8.6 times the space!

The following chart compares different encoding rates and file sizes for this song:

Bit Rate
Compression Ratio
320 7.5 MB 4.2 to 1
256 6 MB 5.4 to 1
192 4.5 MB 7.3 to 1
160 3.8 MB 8.6 to 1
128 3 MB 10.9 to 1
64 1.5 MB 21.7 to 1

MP3 offers particularly good results with popular music and spoken text, but may not always achieve great results with Art Music (or music that has a broad frequency range).

What is MP3 NOT Good For?