DVD-18 DVD-18 in an acronym that means a two-sided DVD disc with two layers of data on both sides of the disc -- in other terms, it is a two-sided disc that holds DVD-9 disc on both sides of it. DVD-18 disc can contain upto 15.9 gigabytes of data on it (with 7.95 gigabytes on each side). Other regular DVD size acronyms are: -DVD-5 -DVD-9 -DVD-10 -DVD-14 DVD-14 DVD-14 is an oddball format that doesn't really exist anymore, but was used for a short period of time back in late 1990s and in early years of new millennium when manufacturing of DVD-18 discs was complicated and expensive. DVD-14 is a two-sided DVD disc that has one side which contains single layer of data and one side which contains two layers of data. In easier terms, the other side of the disc is DVD-5 and the other side of the disc is DVD-9. DVD-14 disc can hold upto 12.33 gigabytes of data. DVD-10 DVD-10 means a two-sided DVD disc that hold single data layer on both sides. Effectively this means that DVD-10 is a dual-sided DVD-5 and can hold 8.75 gigabytes of data with 4.38 gigabytes on each side. Two-sided discs need to be flipped over in order to access the other data side. Unfortunately many blank DVD media advertisers mislead customers to believe that these discs are actually blank DVD-9 discs in hope that they could copy their dual-layer discs directly to blank discs. But as dual-layer writable blank media is impossible to create, customers get misled. DVD-9 One form of DVD discs that means a single-sided dual-layer DVD disc. DVD-9 can hold approximately 7.95 gigabytes of data, even though marketers like to use the 8.5GB value instead, but this is misleading and is calculated by using so-called "Japanese gigabytes" which means that gigabyte is calculated as 1,000 megabytes, but in real computer terminology, gigabyte is 1,024 megabytes. DVD-9 DVD-Video discs are problematic for DVD-R owners, because writable DVD discs can only hold the same amount of data that DVD-5 discs contain, due technical reasons. DVD-5 DVD-5 is an acronym that means a DVD disc that is one-sided single-layer disc and can contain upto 4.38 gigabytes of data on it. DVD disc manufacturers love to use marketing terms and sell their discs as 4.7GB discs, but this is not true -- the 4.7GB is calculated by using so-called "Japanese gigabytes", where the power of calculations is 1,000 instead of 1,024 (and 1.024 is the correct way to calculate everything in computer world -- so, 1024 megabytes == 1 gigabyte). DVD-5 DVD-Video discs are nice, because DVD writers (this applies to both, DVD-R and DVD+R standards) can only write single layer discs.