What are the different sizes for DVDs?
There are many variations on the DVD theme. Discs come in two physical sizes: 12 cm (4.7 inches) and 8 cm (3.1 inches), both 1.2 mm thick, made of two 0.6mm substrates glued together. These are the same form factors as a CD. A DVD can be single-sided or double-sided. Each side can have one or two layers of data. The amount of video a disc can hold depends on how much audio accompanies it and how heavily the video and audio are compressed. The oft-quoted figure of 133 minutes is apocryphal: a DVD with only one audio track easily holds over 160 minutes, and a single layer can actually hold up to 9 hours of video and audio if it’s compressed to VHS quality.
