I have a late 2012 13 inch MBA When I bought it the advertised battery life was 7:30 hours I believe. I think with web browsing, watching youtube videos, listening to music I get about 6 hours. I honestly don't think I ever got 7:30 hours of battery life out of this machine. When I'm on battery I keep the brightness pretty low, usually 50% or lower. I suppose I might get 7 hours if I literally did nothing but browse websites, not watch any video/flash, and maybe some word processing. It kind of bugs me that the 2013 Air basically doubled the battery life, if I had known the difference was going to be that drastic I might have waited.