Calorie Calculator
Calculate how many calories you need each day to maintain, lose, or gain weight. This calculator uses the Mifflin-St Jeor equation — the gold standard recommended by nutritionists — combined with your activity level.
Formula reviewed for accuracy. Our methodology & sources
Calorie Calculator
health calculator
How It Works
Your daily calorie needs are built in two steps. First the calculator finds your Basal Metabolic Rate (BMR) — the energy your body burns at complete rest just to keep you alive, running your heart, lungs, brain, and cell repair. It uses the Mifflin-St Jeor equation, which research has found to be the most accurate of the common formulas for the general population: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5, and for women the final term is −161 instead of +5. Second, it multiplies your BMR by an activity factor between 1.2 (sedentary) and 1.9 (very active) to estimate your Total Daily Energy Expenditure (TDEE) — the calories you actually burn across a full day including movement and exercise. Work through an example. A 30-year-old man weighing 70 kg at 175 cm has a BMR of (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 700 + 1,093.75 − 150 + 5 ≈ 1,649 calories a day at rest. At a moderate activity factor of 1.55, his TDEE is about 1,649 × 1.55 ≈ 2,556 calories a day. Eating around that amount holds his weight steady. To lose weight the calculator subtracts about 500 calories to give roughly 2,050, and to gain it adds 500 — because a deficit or surplus of about 500 calories a day corresponds to roughly 0.5 kg (1 lb) of weight change per week. Use these numbers as an informed starting point, then adjust based on real results. The activity multipliers are broad estimates, and people routinely overestimate how active they are, so if the scale is not moving as expected after two or three weeks, revise your intake rather than trusting the formula blindly. Two safety pitfalls matter most: do not cut calories too aggressively — dropping below about 1,200 a day for women or 1,500 for men without medical supervision risks muscle loss and nutrient shortfalls — and remember the equation estimates energy quantity only, not diet quality. Protein, fibre, and micronutrients matter for health and satiety even when the calorie total is correct. Pregnant or breastfeeding women, athletes, and anyone with a medical condition should treat these figures as rough and consult a professional.
Formula
BMR (men) = 10×weight + 6.25×height − 5×age + 5 BMR (women) = 10×weight + 6.25×height − 5×age − 161 TDEE = BMR × Activity Factor
Examples
30yo male, 70kg, 175cm, moderate activity
A typical active adult male needs around 2,600 calories to maintain weight.
Frequently Asked Questions
How many calories should I eat to lose weight?
To lose weight you need to eat fewer calories than you burn. A daily deficit of about 500 calories below your TDEE produces roughly 0.5 kg (1 lb) of fat loss per week, a rate most experts consider safe and sustainable. Avoid dropping below about 1,200 calories for women or 1,500 for men without medical supervision, as very low intakes risk muscle loss and nutrient deficiencies.
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — the total calories your body burns in a full day, combining your resting metabolism with all physical activity and exercise. It is your BMR multiplied by an activity factor. Eating at your TDEE maintains your current weight, eating below it causes weight loss, and eating above it causes weight gain.
What is BMR?
BMR, or Basal Metabolic Rate, is the number of calories your body burns at complete rest simply to stay alive — powering breathing, circulation, temperature regulation, and cell repair. It typically accounts for 60–75% of the calories you burn each day. Larger, younger, and more muscular bodies generally have a higher BMR.
Why does this calculator use the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation, published in 1990, is widely regarded as the most accurate BMR formula for the general population and is recommended by many dietitians over older equations like Harris-Benedict. It was validated against measured metabolic rates and tends to predict resting energy expenditure with less error. That reliability is why it has become the standard in nutrition practice.
How accurate are the calorie estimates?
These figures are well-founded estimates, not exact measurements, because everyone's metabolism, genetics, and true activity level differ. The activity multipliers in particular are broad, and most people overestimate how active they are. Use the result as a starting point and adjust your intake up or down based on how your weight actually changes over two to three weeks.
How should I choose my activity level?
Pick the level that reflects your typical week, and lean conservative if unsure. Sedentary (1.2) suits a desk job with little exercise; light (1.375) fits one to three workouts a week; moderate (1.55) fits three to five; active (1.725) fits six to seven; and very active (1.9) is for hard daily training or physically demanding jobs. Overstating your activity is the most common reason people eat more than they burn.
Is a 500-calorie deficit right for everyone?
A 500-calorie deficit is a reasonable default that yields about 0.5 kg (1 lb) of loss per week for many people, but it is not universal. Smaller or less active individuals may find 500 too aggressive and should use a gentler deficit, while larger individuals can sometimes sustain a bigger one. The safest approach is a moderate deficit combined with adequate protein and strength training to preserve muscle.
Sources
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