A compact disc's information capacity is between 650 and 700 megabytes. Typically, approximately 50 megabytes are used for the purposes of file structure and indexing.
Audio compact discs, which feature uncompressed digital audio files, take up more space than compressed audio files like the popular MP3 format. There is a maximum of 74 minutes of music on an audio CD. As a general rule, one minute of a compressed audio file is approximately equal to 1 megabyte of data. Thus, a 700-megabyte CD can hold close to 700 minutes of compressed music files.
The storage capacity of a CD is divided into minutes, seconds and sectors. There are 75 sectors per second, 60 seconds per minute and 74 minutes per disc on high-capacity types.