There are many factors that come into play when finding how much data a movie will take. It depends on the quality, your connection speed, the size of the movie, what source you are watching the movie on and other factors. On average at 1080p a 2 hour movie would use about 7 or 8 Gbps. If you were to watch a movie at a different quality like 720p, you would use about 0.9GB per hour. 2K and 4K would use about 3 GB and 7.2 GB an hour, which doesn’t put into account other factors. If you are using Netflix to stream a two hour movie then you will use about 2 GB in SD. You will use about 6 GB to stream in HD or 14 GB for a two hour movie in 4K. Amazon prime doesn't use as much data as Netflix does to stream a movie so if you were worried about data and had to choose between the two, Amazon would be the better option. On Amazon watching a movie in SD a two hour movie would use about 1.6 GB. For a two hour movie in HD and in (Ultra High Definition) UHD Amazon would use about 4 GB and 12 GB respectively. This is about three quarters of the data Netflix would use. It all depends on the settings you watch movies on though.