Data isn't like a gas tank on a car where you can be reasonably sure that X gallons=X miles. Though speed and driving conditions can vary that number somewhat the number should be close to what you can get. In fact your question is more like asking 16 gallons of gas = how many hours of driving? Doesn't really make sense.
As was said a Netflix movie can be more than 2 GB per hour. Though that's more likely if your outputting it to a TV than on a phone, but who knows. My Lucid only uses about 350 MB per hour on Netflix as far as I can tell. A Razor Maxx with a bigger screen with more pixels and more oomph under the hood probably uses more. Whether that's 2 GB an hour who knows. Even the lowest quality YouTube type video you will be watching will use a lot of data. Probably in excess of 150 MB an hour minimum. Best to use wi-fi if you can whenever you are watching video.
Streaming music like Pandora or Spotify can vary also. Typically most streaming music is between 128 kbps and 192 kbps( between 56 MB - 84 MB per hour ) though Spotify premium is 320 kbps( 140 MB per hour ). My ESPN radio app uses less than 50 kbps.
Just browsing websites checking e-mail won't use a lot of data.
For the record 1024 MB = 1 GB. In case you were not aware.
