Technically, on your system it would be 4.37 GB for DVD-5 (commonly called 4.7 GB media), 8.75 GB for DVD-10 (double sided single layered) which is what movies are placed on, 7.95 GB for DVD-9 (commonly called DL or 8.5 GB media), then 15.9 GB for DVD-18 (double sided dual layered).