Calculator
BMR Calculator
Estimate basal metabolic rate using the Mifflin-St Jeor equation. Learn what BMR represents, how it differs from TDEE, and why the estimate varies between people.
Estimate BMR
Your estimate
What BMR means
Basal metabolic rate (BMR) is an estimate of the energy your body would use at rest under the conditions represented by the selected predictive equation. It is not your total daily calorie requirement. Everyday energy expenditure also includes movement, exercise, digestion, and other processes.
Mifflin-St Jeor formula
Women: BMR = 10W + 6.25H − 5A − 161
W = weight in kg; H = height in cm; A = age in years
This calculator uses the Mifflin-St Jeor predictive equation. The original research described a new predictive equation for resting energy expenditure; the equation remains a commonly used estimation method.
Worked example
For a hypothetical 30-year-old man weighing 70 kg and measuring 175 cm: 10×70 + 6.25×175 − 5×30 + 5 = 700 + 1093.75 − 150 + 5 = 1,648.75 kcal/day. The calculator displays the estimate rounded to the nearest whole calorie.
BMR versus TDEE
BMR is a resting estimate. TDEE is a broader estimate that applies an activity factor to BMR. If your goal is to understand approximate daily energy needs, continue to the TDEE Calculator.
What can affect the estimate?
Predictive equations cannot capture every individual difference in body composition, genetics, health status, training, or measurement error. Two people with the same age, height, weight, and sex inputs can still have different measured energy expenditures.
Limitations
- BMR is estimated, not directly measured.
- The equation is a population-based prediction.
- Sex is an input to the selected equation; it is not a statement that human physiology fits only two categories.
- The result should not be used as a medical prescription.
Frequently asked questions
What is BMR?
BMR is an estimate of resting energy expenditure using a predictive equation.
How is BMR calculated here?
This tool uses the Mifflin-St Jeor equation with age, sex, height, and weight.
Is BMR the same as maintenance calories?
No. Maintenance calories are better represented by an estimate of total daily energy expenditure.
Does BMR change with age?
Age is a variable in the equation, and energy needs can also change as body composition and other factors change.
Why is BMR only an estimate?
Predictive equations cannot capture every individual physiological difference.
Can I use BMR to set calories exactly?
No. It is a starting estimate; actual energy needs can differ.
What should I use after BMR?
TDEE adds an activity assumption to estimate daily energy expenditure.
Can measured resting energy expenditure differ from BMR?
Yes. Real-world measurements and the conditions under which they are taken can differ from a predictive estimate.