Home › Nutrition Calculators › Basal Metabolic Rate (BMR) Calculator
Estimate basal metabolic rate (BMR) using the Mifflin–St Jeor predictive equation. Enter age, body weight and height, then select the equation setting shown in the calculator. The result is an estimate of resting energy expenditure, not a measured metabolic rate or a daily calorie prescription.
Basal metabolic rate calculator
Results are estimates based on the values you enter. Nothing you type is sent to or stored on our servers.
Mifflin–St Jeor equations
For the male equation setting: BMR = 10W + 6.25H − 5A + 5. For the female equation setting: BMR = 10W + 6.25H − 5A − 161. W is body mass in kilograms, H is height in centimeters and A is age in years. The calculator requires positive values for age, weight and height.
Verified numerical examples
For the female equation setting at age 30, weight 65 kg and height 165 cm: BMR = 10(65) + 6.25(165) − 5(30) − 161 = 650 + 1,031.25 − 150 − 161 = 1,370.25 kcal/day, displayed as approximately 1,370 kcal/day.
For the male equation setting at age 30, weight 65 kg and height 175 cm: BMR = 650 + 1,093.75 − 150 + 5 = 1,598.75 kcal/day, displayed as approximately 1,599 kcal/day. These examples verify the arithmetic; they do not imply that the equation perfectly predicts an individual’s metabolism.
How to use the calculator
- Choose the equation setting requested by the interface.
- Enter age in years, weight in kilograms and height in centimeters.
- Calculate and read the estimated BMR in kilocalories per day.
- Use the estimate as one input to further planning only when appropriate; do not treat it as total daily energy expenditure.
BMR is not TDEE
BMR estimates energy use under basal resting conditions. Total daily energy expenditure (TDEE) also includes physical activity, food processing and everyday movement. Multiplying BMR by an activity factor is a separate estimation step and introduces additional uncertainty. A BMR result should not be used alone as a calorie target.
Accuracy and limitations
Mifflin–St Jeor is a population-derived prediction equation. Individual results can differ because of body composition, age, health, medications, hormonal status, measurement error and other factors. The calculator uses a binary male/female equation setting because that is how the implementation is configured; the equation selection may not be appropriate for every individual.
This tool is educational and does not measure metabolism, diagnose a condition or provide medical nutrition advice. If you have a medical condition, are pregnant, are recovering from illness, or need a supervised nutrition plan, consult a qualified healthcare professional or registered dietitian.
Frequently asked questions
Is BMR the number of calories I should eat?
No. BMR is an estimate of basal energy expenditure. Daily energy needs are usually higher and depend on activity and individual circumstances.
Why does the calculator ask for kilograms and centimeters?
Those are the units used in the equation. Convert pounds to kilograms and inches to centimeters before entering values.
Can the result be exact?
No. It is a prediction equation, not a direct measurement. Treat the output as an estimate.
Related tools
For an activity-adjusted estimate, use the Total Daily Energy Expenditure (TDEE) Calculator. For a calorie distribution by macronutrient, see the Macro Split Calculator.