BMR Calculator

BMR (Basal Metabolic Rate) is the number of calories your body burns each day simply to stay alive — to keep your heart beating, your lungs breathing, your brain working and your cells repairing themselves. Even if you spent the entire day lying perfectly still in bed, your body would still burn this many calories. BMR typically accounts for around 60–70% of the total calories most people burn each day, which makes it the single most important number for anyone trying to lose, maintain or gain weight.

This calculator uses the Mifflin-St Jeor equation, which medical researchers consider the most accurate BMR formula for the general population. It takes into account your weight, height, age and gender, because each of these factors changes how many calories your body needs at rest. Younger people, heavier people, taller people and men generally have a higher BMR than older, lighter, shorter people and women.

To turn your BMR into a useful daily calorie target, multiply it by an activity factor — that gives you your TDEE (Total Daily Energy Expenditure), which is what you actually burn including walking, working, exercise and digestion. Use the activity table above to pick the multiplier that honestly matches your week. From there, adjust based on your goal: eat 300–500 calories below your TDEE to lose weight steadily, eat at your TDEE to maintain, or eat 300–500 calories above to build muscle. For best results, recalculate every few weeks as your weight changes, weigh yourself at the same time of day, and pair this with consistent strength training and protein intake.