Based on the Mifflin-St Jeor equation used by registered dietitians
The average adult woman needs approximately 1,600-2,400 calories per day and the average adult man needs 2,000-3,000 calories depending on age height weight and activity level. To lose 1 pound per week create a deficit of 500 calories per day. To gain 1 pound per week add 500 calories per day above your maintenance level.
Daily calorie needs are calculated using the Mifflin-St Jeor equation — the formula most widely used by registered dietitians and considered the most accurate for estimating basal metabolic rate. Your BMR is then multiplied by an activity factor to give your total daily energy expenditure.