BMR Calculator
Compare Mifflin-St Jeor and revised Harris-Benedict estimates of daily resting energy needs. Enter adult age, sex, height, and weight using US or metric measurements.
BMR Calculator tool
About the BMR Calculator
An activity table translates each resting estimate into approximate daily expenditure. Results are estimates and not medical advice; resting energy is not a prescribed calorie intake.
How Is BMR Calculated?
The equations below describe the calculation. Use the units specified in each expression; results are rounded for display.
Mifflin male = 10 × kg + 6.25 × cm − 5 × age + 5
Mifflin female = 10 × kg + 6.25 × cm − 5 × age − 161
Revised Harris male = 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age
Revised Harris female = 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
Daily expenditure = resting estimate × activity factor
Example
For a male age 30, 80 kg, 180 cm, Mifflin gives 1780 kcal/day and revised Harris-Benedict gives 1853.63 kcal/day.
How to Use the BMR Calculator
- Choose US customary or metric units.
- Enter your height; in US units, use whole feet and remaining inches from 0 to less than 12.
- Enter your age (20–120), sex used by the equation, and current weight.
- Read the live result and calculation breakdown; correct any validation messages.
- Use Reset to restore the sample values, or copy the result for discussion with a clinician.
BMR Calculator Examples
Male comparison
At age 30, 80 kg and 180 cm, Mifflin is 1780 kcal/day. Sedentary expenditure at 1.2 is 2136 kcal/day.
Female comparison
At age 30, 80 kg and 180 cm, female Mifflin is 1614 kcal/day and revised Harris-Benedict is 1615.09 kcal/day.
BMR versus resting energy
Strict BMR measurement requires controlled conditions. Prediction formulas are practical estimates rather than laboratory measurements.
Appropriate users
This tool accepts ages 20–120 and is an adult planning aid. Illness, medication, pregnancy, and unusual body composition can limit accuracy.
Frequently Asked Questions
Which Harris-Benedict version is used?
This calculator uses the Roza and Shizgal 1984 revision, not the original 1919 coefficients.
Why do the formulas disagree?
They were developed from different populations and use different coefficients. Neither measures your personal metabolism directly.
Is BMR my maintenance intake?
No. Maintenance also includes digestion and movement. The activity table provides a rough expenditure estimate.
What are the activity factors?
The table shows sedentary 1.2, light 1.375, moderate 1.55, very active 1.725, and extra active 1.9.
Can I measure my metabolism?
Clinicians can assess resting energy expenditure with indirect calorimetry when appropriate. Even measured resting energy is not total daily expenditure.