WAV Files

WAV files are in effect uncompressed (comparatively, if not always actually). WAV was the format that Microsoft released with windows years ago: most sounds that your PC makes (e.g. the 'new e-mail received' sound) are WAV files. As far as file size goes, it varies greatly, but they are about 10 times as big as MP3s of the same recording. The amount depends a lot on the complexity of the tune, but as a general rule, wav files are ENORMOUS in comparison to modern compressed audio files such as MP3 and WMA.

WAV can record sounds at very high quality rates, however. Even slightly better quality than you get on a CD in some cases. This is why WAV files, although huge and ungainly, are frequently used as source files for more ruthless compression methods.

E.g. a 3 Minute WAV recording might be 40 MB. From this 40 MB wav file it is relatively easy to make a 3 MB MP3 or 2MB WMA because the 40MB wav file contains a lot of data.

Turning an already highly compressed file (e.g. a WMA) into another highly compressed format (e.g. MP3) is not quite as easy, as you have already removed and stripped out a lot of the source data through the original conversion (into WMA).