The number of minutes on a blank CD varies according to size, but a standard 12-centimeter blank CD has either 74 or 80 minutes available. For an 8-centimeter blank CD, 21 minutes is the industry standard.
According to the Optical Storage Technology Association, the standard size for a CD is either 8 or 12 centimeters. The latter is much more popular with consumers because it can hold more data, typically 650 or 700 megabytes. These two sizes can store 74 minutes and 80 minutes respectively. On the other hand, an 8 centimeter CD has a size of 185 megabytes and can hold just 21 minutes of audio.