Not quite 4 hour, but probably a good two. But definitely every day. At work I take a quick note, but it's not like hours, but then I might reference a material I have stored there too, so it all depends. I use it in bits and pieces. Surf, do something else. Read an e-book; then put my laundry away. But then there are times I'm on iPad for an hour straight reading a book or surfing, so I would say I average more than an hour, but less than 4.