Calorie Calculator
Estimate your daily calorie needs with the Mifflin-St Jeor equation. Enter your age, sex, height, weight, and activity level to get your BMR, maintenance calories, and targets for losing or gaining weight.
Knowing how many calories your body burns each day is the starting point for any diet plan. This calculator uses the Mifflin-St Jeor formula — the equation most dietitians and researchers rely on — to estimate your basal metabolic rate (BMR) and total daily energy expenditure (TDEE), plus simple daily targets for losing or gaining about a pound per week.
How to use this calculator
- Enter your age in years.
- Select your sex (the formula differs for men and women).
- Enter your height in centimeters and weight in kilograms.
- Choose the activity level that best matches a typical week.
- Click Calculate to see your BMR, maintenance calories, and weight-loss or weight-gain targets.
The formula
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. TDEE = BMR × activity factor (1.2 sedentary to 1.9 extremely active).
Worked example
A 30-year-old man who is 180 cm tall and weighs 80 kg has a BMR of 1,780 calories per day. With a sedentary lifestyle (activity factor 1.2), his maintenance target is 2,136 calories — about 1,636 calories per day to lose roughly a pound a week, or 2,636 to gain.
Frequently Asked Questions
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is a formula that estimates your basal metabolic rate — the calories your body burns at rest — from your weight, height, age, and sex. Published in the American Journal of Clinical Nutrition in 1990, it is widely considered the most accurate BMR formula for the general population and is the equation most dietitians use. Our calculator then multiplies your BMR by an activity factor to estimate your total daily energy expenditure (TDEE).
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the number of calories your body needs just to keep you alive at complete rest — breathing, circulation, cell repair. TDEE (total daily energy expenditure) adds the calories you burn through everything else: walking, working, exercising, even fidgeting. TDEE is the number that matters for diet planning, because eating at your TDEE keeps your weight stable, eating below it creates the deficit needed to lose weight.
How do I use these numbers to lose weight?
A daily deficit of about 500 calories typically produces weight loss of roughly one pound per week, since a pound of body fat stores about 3,500 calories. The calculator's 'lose target' is simply your TDEE minus 500. Most people do best with a moderate deficit rather than an extreme one — very low calorie intakes are hard to sustain and can cost you muscle. Pair the target with regular activity and enough protein for the best results.
Why does the calculator ask for my activity level?
Two people with identical height, weight, age, and sex can burn very different amounts of energy if one sits at a desk all day and the other works construction. The activity multipliers — 1.2 for sedentary up to 1.9 for extremely active — adjust your BMR to reflect real life. Be honest here: most people overestimate their activity, and picking a level too high makes the maintenance target too generous.
How accurate is this calorie estimate?
For most healthy adults it lands within about 10% of what lab measurement would find, which is good enough for diet planning. But it is still an estimate: muscle mass, hormones, medications, and medical conditions all shift your real burn rate. If your weight isn't moving after two to three consistent weeks at your target, adjust the target by 200–300 calories rather than assuming the formula is exact.