EXAMPLE
A 30-year-old, 180cm, 80kg, moderately active male needs about 2,759 cal/day to maintain weight.
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How this calculator works
Daily calorie needs vary by size, age, sex, and activity level. This calculator estimates calorie needs using basal metabolic rate (BMR) — the energy the body burns at rest — multiplied by an activity level, giving figures for maintaining, losing, or gaining weight.
THE MATH BEHIND IT
BMR (Mifflin-St Jeor): 10 × weight(kg) + 6.25 × height(cm) − 5 × age, adjusted by sex
Daily calories (TDEE): BMR × activity multiplier
Lose / gain weight: subtract or add about 500 calories/day
A real example
A 30-year-old male, 180 cm, 80 kg, with a moderately active lifestyle:
BMR
≈ 1,780 cal/day
Maintain (×1.55 activity factor)
1,780 × 1.55 =≈ 2,759 cal/day
Common questions
Age, height, sex, and activity level all factor into the formula — a taller or younger person generally burns more calories at rest than a shorter or older person at the same weight.
Moderately active corresponds to exercise roughly 3–5 days a week. Very active corresponds to hard exercise 6–7 days a week, or a physically demanding job.
Calorie formulas are estimates based on population averages, not a direct measurement of individual metabolism — different formulas (this one uses Mifflin-St Jeor) can produce slightly different estimates for the same inputs.