Knowledge is power.
This calculator gives you a great estimate of the calories you burn everyday, so you can go after the body you want. Lose fat, or gain muscle - this number is your bible.
This calculator will tell you your BMR (Basal metabolic rate), which is the minimum number of calories you need at rest to power functions like heart beat, temperature and breathing. Your TDEE (Total Daily Energy Expenditure) is the amount of calories you burn factoring in your BMR, AND the exercise you're doing!