BMR

BMR (Basal Metabolic Rate) is the energy your body uses at complete rest, lying down, awake, fasted, in a thermally-neutral environment. It accounts for the calories needed to sustain core biological functions — heart, lungs, brain, liver, kidneys — without any physical activity.

Typical BMR is 1200-1800 kcal/day for adult women, 1400-2200 for adult men, varying with weight, height, age, and muscle mass. The most accurate predictive formula for modern adults is Mifflin-St Jeor (1990):

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 is the foundation for TDEE (total daily energy expenditure) — multiply BMR by an activity factor and you get the calories needed to maintain weight. Use our BMR calculator for both.