The amount of data you use while streaming varies by platform, and what resolution you’re watching in. According to self-reported data from the major streaming services, bandwidth can go as low as hundreds of megabytes per hour for low-definition (480p) video, which you might watch on a phone, but for the more standard HD/1080p streaming services report 2 to 3 GB per hour. 4K video brings that up to 7 or 8 GB per hour (varying from video to video, of course).