BMR Formula (Basal Metabolic Rate)
Calculate Basal Metabolic Rate using the Harris-Benedict equation.
Separate formulas for men and women in both metric and imperial units.
The Formula
Harris-Benedict Equation (Revised)
Men (metric):
Women (metric):
BMR is the number of calories your body burns at complete rest just to maintain basic life functions.
This includes breathing, circulation, cell production, and nutrient processing.
Variables
| Symbol | Meaning |
|---|---|
| BMR | Basal Metabolic Rate (calories per day) |
| weight | Body weight in kg (1 kg = 2.205 lbs) |
| height | Height in cm (1 inch = 2.54 cm) |
| age | Age in years |
Imperial Conversions
If you use pounds and inches, convert first:
- Weight: kg = lbs ÷ 2.205
- Height: cm = inches × 2.54
Example 1 (Men, Metric)
A 30-year-old man weighs 80 kg and is 180 cm tall. What is his BMR?
BMR = 88.362 + (13.397 × 80) + (4.799 × 180) - (5.677 × 30)
BMR = 88.362 + 1,071.76 + 863.82 - 170.31
BMR ≈ 1,853.6 calories per day
Example 2 (Women, Imperial converted to Metric)
A 25-year-old woman weighs 140 lbs and is 5'6" tall. What is her BMR?
Convert: weight = 140 ÷ 2.205 = 63.5 kg
Convert: height = 66 inches × 2.54 = 167.6 cm
BMR = 447.593 + (9.247 × 63.5) + (3.098 × 167.6) - (4.330 × 25)
BMR = 447.593 + 587.18 + 519.23 - 108.25
BMR ≈ 1,445.8 calories per day
When to Use It
Use the BMR formula when you need to:
- Estimate your base calorie needs before accounting for activity
- Create a starting point for weight management plans
- Calculate TDEE (Total Daily Energy Expenditure) by multiplying BMR by an activity factor
BMR typically accounts for 60-75% of total daily calories burned.
To find your total daily calorie needs, multiply BMR by your activity level factor (see the TDEE formula).
This formula is for general educational purposes only. It is not medical advice. Consult a healthcare professional for personal nutrition planning.