This is predetermined when you enterered your health profile on the phone and you entered your weight,height,gender etc.
Resting Calories
Your resting calories per day is the amount of energy (in the form of calories) that your body needs to function while resting. This is also known as BMR, or Basal Metabolic Rate. This number of calories reflects how much energy your body requires to support vital body functions. In fact, your BMR is the single largest component (upwards of 60 percent) of your total energy burned each day.
Basically, your body burns calories just by doing nothing, and this is the number those calories are.