Calorie Calculator
How many calories you burn per day, and what to eat to maintain, lose, or gain weight.
How your calorie needs are estimated
Your basal metabolic rate (Mifflin-St Jeor) is multiplied by an activity factor from 1.2 (sedentary) to 1.9 (extra active) to give TDEE, your total daily energy expenditure. Eat that to stay where you are. A deficit of roughly 500 kcal/day works out to about 0.5 kg (1 lb) of weight loss per week, since half a kilo of body fat stores about 3,500 to 3,850 kcal.
Honest caveats
These are estimates with real error bars. Individual metabolisms vary ±10% or more, people overestimate activity level, and TDEE drops as you lose weight (recalculate every 5 kg). Treat the number as a starting point and adjust based on 2 or 3 weeks of actual results. Most adults shouldn't eat below ~1,500 kcal (men) / ~1,200 kcal (women) without medical guidance.