I average about 3-6 hours in Mac OS X based on what I'm doing and how much time the computer goes into sleep mode. Not really the 10 hour advertised limit but much higher than I'm used to. The computer does not stay on the charger until I get home. I only average 2-3 hours if I'm using Windows 7 via Boot Camp. The computer under Mac OS X likes to jump around when calculating battery life. It will go from 3 hours to 7 hours to 4 hours to 2 hours. Generally, I'll get a maximum of 6. I thought I calibrated it, but how do I get it to display more accurately?