BMR Calculator
Estimate your daily calories burned at rest.
kg or lb
cm or in
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
Basal Metabolic Rate is the energy your body spends at complete rest just to keep essential systems running: circulation, breathing, cell repair, brain activity and temperature regulation. It represents the largest slice of most people's daily calorie burn, typically 60 to 70 percent, which is why any bmr calculator sits at the foundation of nutrition planning. This bmr calculator uses the Mifflin-St Jeor equation, published in 1990 after the authors measured resting energy expenditure by indirect calorimetry in hundreds of adults and fitted a regression to weight, height, age and sex. Validation studies have since shown it predicts resting metabolism more accurately for today's populations than the older 1919 Harris-Benedict equation, which tended to overestimate. That accuracy is why registered dietitians, sports scientists and weight-management clinics adopted it as their default. Age enters the equation because metabolism slows as lean tissue declines over the years, and sex is included because men generally carry more muscle, which is metabolically active. The sedentary maintenance figure shown here multiplies your result by 1.2 to approximate daily needs with little exercise. Anyone setting calorie targets for fat loss, maintenance or muscle gain starts from a bmr calculator, then layers activity on top to reach total daily needs.
Mifflin-St Jeor: BMR = 10×kg + 6.25×cm − 5×age + s (s = +5 male, −161 female)
The coefficients come from regression on indirect-calorimetry data. Each kilogram of body mass adds about 10 kcal and each centimetre of height 6.25 kcal, since larger bodies have more metabolising tissue. Age subtracts 5 kcal per year to reflect declining lean mass over time, and the sex constant (+5 for men, −161 for women) captures men's typically higher proportion of metabolically active muscle.
Source:Mifflin MD et al., Am J Clin Nutr. 1990;51(2):241-247
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter sex, age, weight and height.
- 2
Adjust the options
Adjust units if they apply — sensible defaults are already set.
- 3
Read your result
BMR updates instantly as you type — no button to press.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy you burn at complete rest for vital functions only. TDEE, or Total Daily Energy Expenditure, takes that BMR and multiplies it by an activity factor to fold in walking, exercise and the effort of digesting food. BMR is the floor; TDEE is what you actually spend across a full day. You eat around TDEE to maintain weight, not around BMR.
How accurate is the Mifflin-St Jeor equation?
It predicts resting metabolism within about 10 percent for roughly 80 percent of healthy adults, and outperforms the older Harris-Benedict formula for modern populations. Accuracy drops for people at the extremes of body composition, such as elite athletes or those with obesity, because the equation cannot see how much of your mass is muscle versus fat. For most people it is the best estimate without lab testing.
Should I eat exactly my BMR calories?
No. BMR covers only resting functions, so eating at that level while living an active life creates a large, unintended deficit. Your realistic intake for maintenance is BMR multiplied by an activity factor. Even for weight loss, dropping to bare BMR is rarely advised. Use your TDEE as the reference point and apply a moderate deficit from there instead, rather than eating down at your resting rate.
What is a normal BMR for men and women?
It depends on size and age, but a typical adult man falls near 1,600 to 1,900 kcal per day and a typical woman near 1,300 to 1,500, because men usually carry more lean mass. There is no single correct value: taller, heavier and younger people burn more at rest. Your own figure from this equation matters more than any average.
How often should I recalculate my BMR?
Recalculate whenever your weight changes by a few kilograms, since body mass is the biggest driver of the result. A significant shift in muscle from training, or simply getting older by a year or two, also nudges it. Checking every one to two months during an active weight-change phase keeps your calorie targets aligned; there is little value in daily recalculation.