BMR Calculator
BMR Calculator uses the Mifflin–St Jeor predictive equation with weight, height, age, and the equation's sex-specific constant. The output estimates resting energy expenditure in kilocalories per day; it is not a measured metabolic rate or a personal calorie prescription. Illness, pregnancy, body composition, medication, growth, and individual physiology can make actual needs differ.
Runs locally — files stay on your deviceWhat formula does the BMR calculator use?
It uses 10×weight + 6.25×height − 5×age, then adds 5 for the male equation or subtracts 161 for the female equation.
Formula: Estimated kcal/day = 10W + 6.25H − 5A + s
Predictive BMR equations estimate resting expenditure
W is kilograms, H is centimetres, A is years, and s is the equation's sex-specific constant. The original equation was derived statistically from measured resting energy expenditure in a study population, so an individual's value can lie above or below the prediction.
How it works
Enter measured values and select the formula branch requested by the equation. Use the estimate as a starting reference; indirect calorimetry and qualified clinical assessment are more appropriate when precision affects medical or nutrition care.
Key concepts
Resting expenditure is not total daily expenditure
Movement, exercise, digestion, and other daily activity add to resting energy use.
The sex field belongs to this equation
The two constants reflect the published predictive model; they do not describe every individual's physiology or identity.
When to use it
- Understand the Mifflin–St Jeor arithmetic.
- Create a general resting-energy starting estimate.
- Compare how age, height, or weight changes the equation output.
When not to use it
- Do not treat estimated BMR as total daily energy expenditure.
- Do not use it as a treatment target for an eating disorder or medical condition.
- Do not assume the equation captures pregnancy, growth, fever, medication, or unusual body composition.
Worked examples
Worked male-equation example
- Input
70 kg, 175 cm, age 30- Expected output
10×70 + 6.25×175 − 5×30 + 5 = about 1,649 kcal/day
This is a prediction, not a measured result.
Female-equation branch
- Input
Same measurements with −161 constant- Expected output
About 1,483 kcal/day
Only the published constant changes between branches.
Measured versus estimated
- Input
Indirect calorimetry differs from formula- Expected output
Use measured value in the clinical context
Population equations have individual error.
Common mistakes
Calling BMR a calorie target
Food needs also involve activity, goals, health, and individual response. Correction: Use professional guidance for intake decisions.
Entering pounds and inches
The equation expects kilograms and centimetres. Correction: Convert measurements or use the labeled metric fields.
Assuming exact precision
Displayed whole calories can imply more certainty than the model provides. Correction: Interpret the output as an approximate range anchor.
Best practices
- Use accurate metric measurements.
- Keep BMR distinct from TDEE and calorie intake.
- Consult a qualified professional when energy planning affects health.
Related operations and differences
TDEE Calculator
Choose TDEE Calculator when you need to estimate daily energy use from a BMR and activity factor.; use BMR Calculator specifically for bmr.
BMI Calculator
Choose BMI Calculator when you need to estimate body mass index locally for general information.; use BMR Calculator specifically for bmr.
Maximum Heart Rate Calculator
Choose Maximum Heart Rate Calculator when you need to estimate maximum heart rate from age for general information.; use BMR Calculator specifically for bmr.
Running Pace Calculator
Choose Running Pace Calculator when you need to calculate average minutes per kilometer.; use BMR Calculator specifically for bmr.
Waist-to-Height Ratio Calculator
Choose Waist-to-Height Ratio Calculator when you need to calculate waist circumference divided by height.; use BMR Calculator specifically for bmr.
Water Intake Calculator
Choose Water Intake Calculator when you need to estimate a simple daily water baseline from body weight.; use BMR Calculator specifically for bmr.
Limitations and privacy
- This is a population-based estimate for general information, not a diagnosis, treatment plan, or individualized medical or nutrition advice.
- The equation is a population prediction and may not fit unusual body composition or clinical states.
- The binary formula branches reflect the published equation's constants.
Inputs and estimates remain in this browser. Toolbox does not store or transmit these health-related values.
Frequently asked questions
Is BMR the same as TDEE?
No. TDEE adds activity and other daily energy expenditure.
Is this a measured metabolic rate?
No. It is a predictive equation.
Why does the formula ask for sex?
The published equation uses two different constants.
Can I use BMR as my daily calorie intake?
Not by itself; intake planning requires total expenditure, goals, and health context.