Why does my iPhone 4S turn off at 10% battery power?

My iPhone turns off at 10% instead of 0% and I can't figure out why. I went on google and tried searching but I couldn't find a viable solution. Can you tell me the problem and how to fix it?

Perhaps the battery is improperly calibrated? Let it charge to 100 percent and leave it on the charger over night. Then let it run down until it shuts itself off. It could fix it?