What is basal metabolic rate?
Even if you stayed in bed all day, your heart, lungs, brain and liver would keep working. The energy for that is your BMR. It's the biggest part of what you burn, usually 60 to 70%. Exercise and daily movement make up most of the rest, and digesting food adds about 10%.
Bigger bodies burn more, so BMR rises with weight and height. It drops slowly with age, and men tend to be higher than women of the same size because they carry more muscle on average.
How to calculate BMR
Nobody measures BMR at home. It takes a lab and a gas mask. Formulas estimate it from age, sex, height and weight instead. These are the three this calculator uses:
Mifflin-St Jeor (1990)
Men: 10 × kg + 6.25 × cm − 5 × age + 5
Women: 10 × kg + 6.25 × cm − 5 × age − 161
Revised Harris-Benedict (1984)
Men: 88.36 + 13.40 × kg + 4.80 × cm − 5.68 × age
Women: 447.59 + 9.25 × kg + 3.10 × cm − 4.33 × age
Katch-McArdle
370 + 21.6 × lean body mass in kg
The first two usually land within 100 kcal of each other. Katch-McArdle ignores age and sex and looks only at lean mass, so it can be off if your body fat number is a guess.
BMR vs. TDEE: what to eat
BMR alone doesn't tell you how much to eat, because you don't spend the day lying still. Multiply it by your activity level to get your total daily energy expenditure. Our TDEE calculator does that and gives targets for losing or gaining weight. If your goal is fat loss, the calorie deficit calculator also shows how long it will take.
Any formula is a starting point. After two or three weeks of tracking, your real weight trend tells you more than an equation can. myCalCoach on Telegram logs your meals from a photo or voice note and sends a weight chart when you ask for it.
Common questions
What is BMR?
BMR (basal metabolic rate) is the energy your body uses at complete rest to keep you alive: breathing, circulation, brain, body temperature. For most adults it is 1,200 to 2,000 kcal a day and makes up 60 to 70% of total daily calories.
How do I calculate my BMR?
The most used formula is Mifflin-St Jeor. Men: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5. Women: the same, but − 161 instead of + 5. A 30-year-old woman who is 165 cm and 60 kg has a BMR of about 1,320 kcal.
What is the difference between BMR and TDEE?
BMR is what you burn lying still. TDEE adds everything else: walking, exercise, digesting food. To get TDEE, multiply BMR by an activity factor between 1.2 and 1.9.
Should I eat my BMR to lose weight?
Usually not. Your BMR is lower than what you burn in a normal day, so eating exactly your BMR is already a deficit, and for active people often a large one. Set your intake from TDEE minus a moderate deficit instead.
Which BMR formula is most accurate?
For most people Mifflin-St Jeor. A 2005 review found it predicted resting energy within 10% in more people than other common formulas. If you know your body fat percentage reliably, Katch-McArdle can be closer for very lean or very muscular people.
Other free calculators
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789.
This calculator gives general estimates and is not medical advice. Thyroid conditions, some medications and pregnancy change your metabolic rate.