// health › Metabolism & Energy
Basal Metabolic Rate — the calories your body burns at complete rest — via the Mifflin-St Jeor equation.
BMR = 10·w(kg) + 6.25·h(cm) − 5·age (+5 male / −161 female)
A mind behind this: Mifflin & St Jeor 1990
Male/female are the formula's defined variants; “Other” uses the midpoint.
Basal Metabolic Rate is the number of calories your body burns just to keep you alive at complete rest — breathing, circulating blood, keeping your organs running, holding body temperature. It is the energy you would use lying still all day, before any movement, eating, or exercise is added on top.
It is the modern standard formula for estimating BMR from weight in kilograms, height in centimetres, and age in years. Men add 5 to the result and women subtract 161, reflecting average differences in body composition. It tends to be more accurate for today's populations than the older Harris-Benedict equation it largely replaced.
The equation was derived with two variants, defined on biological sex, that differ only by a constant (+5 versus -161). 'Other' simply takes the midpoint of the two, giving a reasonable central estimate when neither variant clearly applies. For the most accurate figure, a clinician can measure resting metabolism directly.
The first bar is your estimated BMR in calories per day. The bars beside it are everyday energy references at the same scale — for instance how much energy you burn over a night's sleep — so the abstract calorie number has something familiar to sit against.
BMR is the foundation for working out daily calorie needs. A 30-year-old man, 80 kg and 180 cm, has a BMR near 1,780 kcal; a 30-year-old woman, 65 kg and 165 cm, near 1,370 kcal. Multiply BMR by an activity factor and you get total daily energy expenditure, which nutrition and fitness planning then builds on. It is an estimate, not a prescription.