Mifflin-St Jeor — the formula most dietitians actually use, not the older, less accurate Harris-Benedict. Maintenance calories, a weight-loss or weight-gain target, and a full macro split.
Harris-Benedict is the older, more commonly-copied formula, but it was derived from a 1919 study and consistently overestimates calorie needs by 5-15% for most people today. Mifflin-St Jeor (1990) is more accurate for the modern population and is what registered dietitians actually use in practice.
Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
BMR (Basal Metabolic Rate) is what your body burns lying still all day — organ function, breathing, keeping you warm. TDEE (Total Daily Energy Expenditure) multiplies that by an activity factor to account for movement, exercise and daily life. TDEE is your actual maintenance calorie number.
A 30-year-old male, 80kg, 180cm, moderately active: BMR is 1,780 kcal, TDEE is 2,759 kcal. Targeting a 500 kcal/day deficit for weight loss gives a target of 2,259 kcal/day — roughly 0.45 kg/week of loss, a sustainable rate that avoids the muscle loss and metabolic slowdown that comes with more aggressive deficits.