Blank recordable CD-R and CD-RW discs are available in two capacities: 74 minutes (both CD-R and CD-RW) and 80 minutes (CD-R only at this time). So, if we do the math: 74 min x (60 sec) x (75 sectors) x (2 kbytes) = 666,000 kilobytes = 650 megabytes 80 min x (60 sec) x (75 sectors) x (2 kbytes) = 720,000 kilobytes = 703 megabytes Factory-recorded CDs can be made to hold a little more data. The actual capacities of blank discs can vary slightly; some 74-minute discs can hold up to two minutes more than their stated capacity. However, this is not likely to be evident on the packaging; you will have to find it out by direct experience, or by asking other CD-R users.