BMR Calculator
Estimate Basal Metabolic Rate (BMR) using the Mifflin–St Jeor equation.
Inputs
Result
Enter values on the left and select Calculate to see the result here.
What the BMR Calculator does
- Estimates basal metabolic rate (BMR)—the calories your body may use at rest—based on your entered body details.
- Shows a kcal/day estimate that can be used as a general guide, not as a medical measurement or diet prescription.
- BMR can vary with body composition, hormones, medical conditions, medications, pregnancy, breastfeeding, and activity history.
How to use the BMR Calculator
- Enter your age, sex, height in centimetres, and weight in kilograms.
- Click Calculate to get an estimated BMR in kcal/day based on your inputs.
- Use the result cautiously and speak to a qualified professional for personal health, nutrition, fitness, or weight-loss guidance.
Formula / methodology used
- Uses the Mifflin–St Jeor equation: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + s.
- The calculator uses s = 5 for male and s = −161 for female, matching the formula currently implemented.
- The output is rounded to the nearest whole kcal/day for display.
Example calculation
Female, 30 years old, 165 cm tall, 65 kg.
- BMR = 10 × 65 + 6.25 × 165 − 5 × 30 − 161
- BMR = 650 + 1,031.25 − 150 − 161 = 1,370.25
- Rounded result = 1,370 kcal/day
Result: The calculator estimates a BMR of about 1,370 kcal/day based on those inputs.
Common mistakes and limitations
- BMR formulas are estimates, not indirect calorimetry or another clinical metabolic measurement.
- Results may vary with age, sex, height, weight, body composition, hormones, medical conditions, medications, pregnancy, breastfeeding, and activity patterns.
- The calculator does not diagnose metabolic health or create nutrition, fitness, or weight-loss targets.
Important note
This calculator is a general guide based on your inputs and is not medical, nutrition, fitness, or weight-loss advice.
BMR Calculator FAQs
Is BMR the same as TDEE?
No. BMR is energy at rest. TDEE includes activity and is typically higher.
Why does sex affect BMR?
Equations include sex-based constants because average body composition differs across populations.