Basal metabolic rate
Calories burned at rest, by formula.
- Mifflin-St Jeor (1990)1,799 calories
- Harris-Benedict, revised (1984)1,877 calories
- Harris-Benedict, original (1919)1,889 calories
The BMR formulas
The calculator offers the three equations people use most. Weight goes in as kilograms, height as centimeters, and age as years inside the formulas, and the calculator converts pounds, feet, and inches for you. Results are in calories (the kcal on a nutrition label).
| Formula | Men | Women |
|---|---|---|
| Mifflin-St Jeor (1990) | 10 × kg + 6.25 × cm − 5 × age + 5 | 10 × kg + 6.25 × cm − 5 × age − 161 |
| Harris-Benedict, revised (1984) | 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age | 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age |
| Harris-Benedict, original (1919) | 66.47 + 13.75 × kg + 5.003 × cm − 6.755 × age | 655.1 + 9.563 × kg + 1.850 × cm − 4.676 × age |
Mifflin-St Jeor is the usual pick for healthy adults, though every formula is an estimate. Measuring oxygen use (indirect calorimetry) in a clinic is the gold standard.
From BMR to daily calories
Total daily energy expenditure (TDEE) is BMR times an activity factor. The multipliers below come from the Harris-Benedict tradition and are widely used. Pick the one that matches a typical week, and be honest about it.
| Activity level | Factor | Daily burn with a BMR of 1,800 |
|---|---|---|
| Sedentary (little or no exercise) | 1.2 | 2.160 calories |
| Lightly active (exercise 1 to 3 days a week) | 1.375 | 2.475 calories |
| Moderately active (3 to 5 days a week) | 1.55 | 2.790 calories |
| Very active (6 to 7 days a week) | 1.725 | 3.105 calories |
| Extra active (hard training or a physical job) | 1.9 | 3.420 calories |
To turn daily burn into a calorie target, use the calorie calculator. For the healthy weight range at your height, see the BMI calculator and the ideal weight calculator.
Limits of the math
- The formulas are for adults. Pregnancy, nursing, kids, frail older adults, and metabolic conditions change energy needs.
- Body composition is not in the math. More muscle means a higher real BMR than the formula shows.
- Use the results as a starting point. A doctor or registered dietitian should guide changes to eating or weight.
Frequently asked questions
What is BMR?
BMR is basal metabolic rate, the energy your body uses at complete rest for breathing, circulation, and keeping warm. It usually makes up the largest share of the calories you burn in a day.
How do I calculate my BMR?
Use Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then add 5 for men or subtract 161 for women. A 25-year-old woman at 132 lb and 5 ft 5 in has a BMR near 1,345 calories.
What is the difference between BMR and TDEE?
BMR counts calories burned at rest. TDEE adds daily movement and exercise, and equals BMR times a factor from 1.2 to 1.9.
Which BMR formula is the most accurate?
Validation studies often find Mifflin-St Jeor closest to measured values in healthy adults, but no formula is exact. Indirect calorimetry is the reference test.
What activity factor should I use?
The common choices are 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, and 1.9 for extra active. Choose the level that fits a normal week, and round down if unsure.
Can I use a BMR calculator if I am under 18?
Not with these formulas, which were built for adults. A pediatrician or dietitian should assess energy needs for kids and teens.
Sources and review
- Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition, 1984.
- Harris JA, Benedict FG. A Biometric Study of Human Basal Metabolism, 1918/1919.