Calorie Calculator

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to keep you alive — breathing, circulation, cell production. This calculator uses the Mifflin-St Jeor equation, which is widely considered the most accurate for most people. For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: same but −161 instead of +5.

TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. It represents the total calories you burn in a day including movement, exercise, and digestion. TDEE is the key number — eating at TDEE maintains your weight, eating below it causes loss, and eating above it causes gain. Most calorie calculators actually give you TDEE, not just BMR.

A deficit of 500 calories/day below TDEE produces roughly 0.5 kg (1 lb) of fat loss per week. A 1,000 calorie deficit targets 1 kg/week, but this is aggressive and harder to sustain. Most experts recommend no lower than 1,200 calories/day for women and 1,500 for men to avoid nutrient deficiencies. Sustainable loss of 0.5–0.75 kg/week is generally more effective long-term than crash dieting.

Building muscle requires a caloric surplus — eating more than your TDEE. A "lean bulk" adds 200–300 calories/day above TDEE for slow, clean muscle gain with minimal fat. An aggressive bulk adds 500+ calories/day. Natural muscle gain is slow regardless — most men can gain 1–2 lbs of muscle per month at best. Higher calorie surpluses don't accelerate muscle growth significantly after a point.

Most people overestimate their activity level. "Sedentary" applies to desk jobs with little to no exercise. "Lightly active" fits someone who walks regularly and works out 1–2x/week casually. "Moderately active" suits consistent gym-goers 3–5x/week. "Very active" is for athletes or people with physically demanding jobs who also train hard. When in doubt, choose one level lower than you think — activity multipliers in formulas tend to run high.

Macronutrients (macros) are protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). Protein is most important for body composition — it preserves muscle during a deficit and supports growth during a surplus. A common target is 1.6–2.2g per kg of bodyweight for active people. This calculator uses ~30% of calories from protein, ~45% carbs, ~25% fat as a balanced starting point, adjusted slightly for goal.

No formula is perfectly accurate — individual metabolism varies by 10–15% from predictions. Use this as a starting point, then track your actual weight for 2–3 weeks. If you're not seeing the expected change (roughly 0.5 kg/week per 500 cal deficit), adjust by 100–200 calories and reassess. The Mifflin-St Jeor equation used here is accurate within ~10% for most people, making it the gold standard among the common formulas.