I do not get 12 hours of battery

Question

Hello. I just purchased my 13 inch "Early 2014" Macbook Air about 4-5 days ago. I never maxed out at 12 hours as advertised, during the time that I've had this computer.
It seems to be 9 hours at best. This is still new so I do not have a bunch of weird settings, all of my settings are still the default apple settings except the one that makes the screen/keyboard bright in dim light. I have disabled that to save battery. This is not my first Macbook, so I've done other things like turning off bluetooth and keeping the brightness below half and I only use Safari not Firefox or Chrome because they drain the battery I read.
Anyways why do I not have 12hours? I've read where even some MBPs have over 12 hours! Here are my specs:
Macbook Air 13 Inch
Manufacture Date: June 30 2014
Max Charge: 7109 mAh, Design capacity: 7150 mAh, 9.2 Watts
Load Cycles: 10
OX S Battery Status: Good
Battery Temperature: 30.7ºC Temp.
Battery
Manufacture Date: May 5, 2014
OSX Battery Status: Good
Battery Temperature: 33.1ºC
Battery Failure: None
Charging with: 11.0 Watts
Power Adapter: 45 Watts
MacBook Air
Manufacture Date: June 30, 2014
Age: 17 Days
OS X Mavericks
All I usually do is surf the web using Safari. I have Mail app open, and if I'm feeling risky I will launch iTunes or the Twitter app. Also on Safari I'm usually on Facebook, Reddit, message boards and infrequently, YouTube. It's not like I stream content all day, my internet is abysmal to the point I can only watch 144p videos.
I have no idea why I can't get 12 hours out of this computer, I've tried timing it with my iPhone from the moment I disconnect. I usually end up charging this Macbook Air at least twice a day. I will wake up to a full charge and it will need to be recharged in the afternoon and again before I go to bed. The condition is listed as "Good" so what do I do? Is this like the iPhone where the only way to actually achieve 12 hours is to basically do nothing on it?

Answer 1

It says:
The 11-inch model gets up to 9 hours of battery life on a single charge and the 13-inch model gets up to 12 hours.
This means once you reduce your energy usage to a barest minimum, then the battery could last up to 12 hours. But that life goes down with any increase in energy usage.
However, if you feel there is a problem, then take it back to have it checked out.