BMR Calculator
Your basal metabolic rate is the energy your body uses just to stay alive — breathing, circulation, cell repair, temperature. It is the floor of your daily calorie burn: everything you do adds on top of it. Every calorie target worth using starts from an accurate BMR.
Fill in the fields above to see your result.
How it's calculated
This calculator uses the Mifflin-St Jeor equation, published in 1990 and validated repeatedly since: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men, and the same formula with −161 in place of +5 for women. The American Dietetic Association's systematic comparison of prediction equations found Mifflin-St Jeor the most reliable across normal-weight and obese adults, which is why it has largely replaced the older 1919 Harris-Benedict equation in clinical and coaching practice.
The inputs matter in intuitive ways: more body mass means more tissue to maintain, so BMR rises with weight and height; metabolism slows modestly with age, hence the age penalty; and the sex constant reflects average differences in lean mass at a given size, since muscle is the most metabolically expensive tissue you carry in quantity. That last point is also the equation's known blind spot — a very muscular person runs hotter than the formula predicts, and a person with high body fat runs slightly cooler, because the equation sees only total weight.
What to do with the number: never eat below it as a long-term strategy, and don't mistake it for a calorie target — BMR is a component, not a goal. Multiply it by an activity factor to get your TDEE (this app's TDEE calculator does exactly that), then set intake relative to TDEE for your goal. If you know your body-fat percentage, compare the result against a lean-mass-based estimate for a second opinion; when the two diverge, the truth is usually in between.
Frequently asked questions
What is a normal BMR?
Most adult men land between 1,500 and 1,900 calories per day, most women between 1,200 and 1,500. Size, age, and muscle mass drive the differences.
Should I eat at my BMR to lose weight?
No. BMR is your resting floor, not a target. Set your deficit against TDEE (BMR × activity). Eating at or below BMR long-term makes training and adherence suffer.
Why Mifflin-St Jeor instead of Harris-Benedict?
Validation studies show Mifflin-St Jeor predicts measured resting metabolism more accurately for modern populations. Harris-Benedict, from 1919, tends to overestimate.
Does muscle really increase BMR?
Yes — lean mass is the biggest controllable driver of resting metabolism. The formula only sees total weight, so very muscular people burn somewhat more than it predicts.
Take it with you
Every calculator, plus workout and macro tracking, in the ElevenSix Fitness app for iPhone.