Daily Calories Intake is determined based on the Basal Metabolic Rate (BMR) calculation.
The BMR calculation using Formula:
   Woman: dci = 655 + 4.35 × w + 4.7 × h - 4.7 × age
   Man: dci = 66 + 6.23 × w + 12.7 × h - 6.8 × age
Where:
   h: Body height, in inches
   w: Body weight, in pounds (lbs)
   age: in years
   dci: Basal Metabolic Rate, in calories

Harris Benedict Formula is then used for Daily Calories Intake calculation:

• sedentary, desk job: Calories = BMR x 1.2
  
• light exercise/sports 1-3 days/week: Calories = BMR x 1.375
  
• moderate exercise/sports 3-5 days/week: Caloriees = BMR x 1.55
  
• hard exercise/sports 6-7 days a week: Caloriees = BMR x 1.725
  
• very hard exercise/sports plus physical job: Calories = BMR x 1.9