How calorie calculator works
Your total daily energy expenditure (TDEE) is the number of calories you burn in a day, combining your Basal Metabolic Rate with the energy used by activity and digestion. To lose weight you eat below TDEE; to gain weight you eat above it. A pound of body fat is roughly 3,500 calories, so a daily deficit of 500 kcal tends to lose about one pound per week.
This calculator first computes your BMR using the Mifflin-St Jeor equation, then multiplies it by an activity factor: sedentary 1.2, light 1.375, moderate 1.55, active 1.725, and very active 1.9. It then reports your maintenance calories plus targets for mild loss (-250), loss (-500), mild gain (+250), and gain (+500).
Pick the activity level that matches an average week, not your best day. Sedentary means a desk job with little exercise; moderate means 3 to 5 workouts a week. The numbers are estimates that assume steady body composition — as you lose or gain weight, recalculate. Treat them as a starting point and adjust based on real results over a few weeks.
Frequently asked questions
How many calories should I eat to lose weight?
A daily deficit of about 500 kcal below maintenance typically loses around one pound (0.45 kg) per week. This calculator shows a "loss" target of maintenance minus 500, plus a gentler "mild loss" of minus 250 for slower, more sustainable progress.
How is my maintenance calorie number calculated?
Maintenance equals your BMR (from the Mifflin-St Jeor formula using your weight, height, age, and gender) multiplied by your activity factor. Sedentary uses 1.2 and very active uses 1.9, with three levels in between.
Which activity level should I choose?
Choose the level that matches a typical week. Sedentary: desk job, little exercise. Light: light exercise 1-3 days/week. Moderate: exercise 3-5 days/week. Active: hard exercise 6-7 days/week. Very active: hard daily training or a physical job.
Are the estimates accurate?
They are good starting estimates based on validated formulas, but real metabolism varies by 10 to 20 percent due to muscle mass, genetics, and health. Track your weight for two to three weeks and adjust your intake based on actual results.