A DVD disc may contain two data layers on each side, or four total, for a maximum capacity of 17.08 GB on a 12 cm disc. Two 0.6 mm thick substrates are bonded to form a 1.2 mm thick disc with data in the middle, similar in form factor to a CD-ROM. The most commonly produced are single-layer, single-sided discs with a 4.70-GB capacity.
A standard CD-ROM holds about 650 megabytes (MB), approximately 0.65 GB. The following list shows the capacity of the various DVD formats, with one or two sides and one or two layers. The DVD-R is a recordable format, the DVD-RAM a rewritable format.
(SS/DS = single-sided/double-sided; SL/DL = single-layer/double-layer)
1 side, 1 layer = 4.7GB capacity
1 siee, 2 layers = 8.5GB capacity
2 sides, 1 layer = 9.4GB capacity
2 sides, 2 layers = 17.0GB capacity
DVD SS/SL: 4.7 GB of data, 2+ hours of video
DVD SS/DL: 8.5 GB of data, 4 hours of video
DVD DS/SL: 9.4 GB of data, 4.5 hours of video
DVD DS/DL: 17 GB of data, 8+ hours of video
DVD-R SS/SL: 3.95 GB of data
DVD-R DS/SL: 7.9 GB of data
DVD-RAM SS/SL: 2.58 GB of data
DVD-RAM DS/SL: 5.16 GB of data