Manufacturers express disc capacity in terms of how much computer data a disc can physically contain in implied binary notations. DVD-R (General), DVD-R (Authoring), DVD+R, DVD+RW and DVD-RAM discs come in 4.7 GB single and 9.4 GB double-sided (12 cm) and 1.46 GB single and 2.92 GB double-sided (8 cm) sizes.

This has not always been the case for DVD-RAM and DVD-R. DVD-RAM discs designed for use in early recorders (version 1.0) come in 2.6 GB single-sided and 5.2 GB double-sided (12 cm) sizes. DVD-R discs compatible with first generation recorders (version 1.0) come in 3.95 GB single-sided and 7.9 GB double-sided (12 cm) and 1.23 GB single-sided and 2.46 GB double-sided (8 cm) sizes.

Manufacturers quote the capacity of a writable DVD disc in decimal (base 10) rather than binary (base 2) notation so a 4.7 GB disc stores 4.7 billion bytes (4,700,000,000 bytes). Expressed in binary notation (as is typical with CD-R, CD-RW and most operating systems) the same disc has a capacity of approximately 4.38 GB (4,700,000,000 bytes ? 1024 = 4.38 GB).

Last update: 04:23 PM Tuesday, March 7, 2006