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BMR Calculator
Estimate adult Basal Metabolic Rate using standard equations. Compare formulas or another weight with metric or imperial measurements. For general adult informational use.
Estimate your Basal Metabolic Rate (BMR), the approximate amount of energy your body uses at rest, using age, height, weight and a standard equation.
BMR is an estimate. Actual metabolic rate can vary with body composition, health, genetics and other individual factors.
For general adult informational use.
Choose BMR Estimate, Formula Comparison or Weight Comparison. Each unit system retains its own entered values; switching units does not convert the input fields. Imperial measurements are converted internally at full precision. BMR is not total daily calorie needs or a calorie-intake recommendation.
Calculations run locally in your browser. Your inputs are not saved.
Enter your measurements and choose an equation.
Example BMR Calculation
Static example: Male Mifflin–St Jeor equation, age 35, height 175 cm and weight 75 kg. BMR = 10 × 75 + 6.25 × 175 − 5 × 35 + 5 = 750 + 1,093.75 − 175 + 5 = 1,673.75 kcal/day, displayed as 1,674 kcal/day. This is an estimate of resting energy expenditure, not a calorie prescription.
About this calculator
How BMR Is Calculated
Both equations use weight in kilograms, height in centimetres and age in years. The formula sex input selects the applicable constants, not a health assessment.
- Mifflin–St Jeor, Male: 10 × weight + 6.25 × height − 5 × age + 5.
- Mifflin–St Jeor, Female: 10 × weight + 6.25 × height − 5 × age − 161.
- Revised Harris–Benedict, Male: 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age.
- Revised Harris–Benedict, Female: 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age.
- Imperial conversion: kilograms = pounds ÷ 2.2046226218; centimetres = (feet × 12 + inches) × 2.54. Unrounded values are used internally.
Understanding the Comparisons
Formula Comparison holds all inputs constant. Weight Comparison holds age, height, formula sex input and equation constant. These are mathematical comparisons, not weight or health recommendations.
- Formula percentage difference = absolute difference ÷ average of the two BMR estimates × 100.
- Weight percentage change = (alternative BMR − current BMR) ÷ current BMR × 100.
- Hourly and minute references divide estimated daily BMR by 24 and 1,440. They do not imply constant real energy expenditure.
Other Static BMR Examples
These examples are informational references, not your calculated results.
- Female Mifflin–St Jeor, age 35, height 175 cm, weight 75 kg: 750 + 1,093.75 − 175 − 161 = 1,507.75 kcal/day, displayed as 1,508.
- Male Revised Harris–Benedict, age 35, height 175 cm, weight 75 kg: 88.362 + 13.397 × 75 + 4.799 × 175 − 5.677 × 35 = 1,734.267 kcal/day, displayed as 1,734.
Frequently asked questions
What is BMR?
Basal Metabolic Rate is an estimate of the energy used by the body at rest under standardized conditions.
How is BMR calculated?
This tool uses age, height and weight in a predictive equation with sex-specific constants. Imperial inputs are converted to metric internally.
What is the Mifflin–St Jeor equation?
It estimates BMR as 10 × weight in kilograms + 6.25 × height in centimetres − 5 × age, plus 5 for the Male equation or minus 161 for the Female equation.
What is the Harris–Benedict equation?
This calculator uses the Revised Harris–Benedict equation. It combines weight, height and age using separate Male and Female coefficients shown above.
Why can BMR equations give different results?
They use different coefficients derived from population data. Neither equation is presented as more accurate for an individual. Actual metabolic rate can differ from either estimate.
Is BMR the same as TDEE?
No. BMR estimates resting energy expenditure. Total Daily Energy Expenditure also includes activity and other energy expenditure. This tool does not calculate TDEE.
Can BMR be used as a calorie prescription?
No. BMR is an estimate of resting energy expenditure and is not a personalized calorie-intake prescription.
This tool provides general informational estimates and is not medical or nutritional advice. BMR equations provide population-level estimates and may not reflect an individual’s actual metabolic rate.