Maintenance and Weightloss Calorie intake algorythm

Men: BMR = 66+(13.7 X wt in kg)+(5 X height in cm) - (6.8 X age in years)
Women: BMR = 655+(9.6 X wt in kg)+(1.8 X height in cm) - (4.7 X age in years)

A better way of calculating your BMR IF You know your amount of lean body mass (body weight - fat mass = lean body mass):
For both men and women it's 370+(21.6 X LBM in kg)

After that, multiply it by your activity factor:

Sedentary = 1.2 (little or no exercise, desk job)
Lightly active = 1.375 (light exercise/sports 1-3 days a week)
Moderately active = 1.55 (moderate exercise/sports 3-5 days week)
Very active = 1.725 (Hard exercise/sports 6-7 days/week)
Extremely active = 1.9 (hard daily exercise, sports and physical job or 2X day training, marathon, football camp, contest etc)

Ok so that's your maintenance level. If you eat that much you'll not lose weight but you won't gain any either (In theory)

Take that amount, and subtract about 20-25% from it, and that's your weight loss level.