How to Calculate Your Basal Metabolic Rate (BMR)
Learn to calculate your Basal Metabolic Rate using Mifflin-St Jeor and Harris-Benedict formulas. Concrete examples and explanations. Track calories with Voical.
Calorie calculation examples by profile
Sedentary woman, 30 years old, 132 lbs, 5'5"
Active woman, 30 years old, 132 lbs, 5'5"
Sedentary man, 30 years old, 165 lbs, 5'10"
Active man, 30 years old, 165 lbs, 5'10"
What is Basal Metabolic Rate?
Basal Metabolic Rate (BMR) represents the energy your body expends at complete rest to maintain vital functions: breathing, blood circulation, organ function, and temperature regulation. It accounts for 60 to 75% of your total daily energy expenditure.
Why know your BMR?
Knowing your BMR is the first step in determining your caloric needs. Multiplied by your activity factor, it gives your TDEE (Total Daily Energy Expenditure). From there, you can create a deficit to lose weight or a surplus to gain. Without this baseline, you're navigating blind.
The Mifflin-St Jeor formula
The Mifflin-St Jeor formula (1990) is considered the most accurate for most adults. Men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5. Women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161. This formula is recommended by the Academy of Nutrition and Dietetics.
Factors affecting BMR
Several factors affect your basal metabolic rate: muscle mass (more muscle means higher BMR), age (BMR decreases about 2% per decade after 20), sex (men generally have higher BMR), and genetics. Prolonged restrictive diets can also temporarily reduce your BMR.
Important
Never go below 1200 kcal/day (women) or 1500 kcal/day (men) without medical supervision. Too aggressive a deficit can be dangerous for your health and counterproductive for weight loss.
Complete Guide to Calculating Your Basal Metabolic Rate
Basal metabolic rate is the foundation of any nutritional strategy. Understanding this number allows you to make informed decisions about your diet.
BMR Calculation Formulas
Mifflin-St Jeor Formula (Recommended)
For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5
For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161
Harris-Benedict Formula (Historical)
For men: BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) - (5.677 x age)
For women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) - (4.330 x age)
Calculation Examples
Example 1: 30-Year-Old Woman
- Weight: 132 lbs (60 kg)
- Height: 5’5” (165 cm)
- Age: 30 years
BMR = (10 x 60) + (6.25 x 165) - (5 x 30) - 161 BMR = 600 + 1031.25 - 150 - 161 BMR = 1,320 kcal/day
Example 2: 30-Year-Old Man
- Weight: 165 lbs (75 kg)
- Height: 5’10” (178 cm)
- Age: 30 years
BMR = (10 x 75) + (6.25 x 178) - (5 x 30) + 5 BMR = 750 + 1112.5 - 150 + 5 BMR = 1,718 kcal/day
From BMR to TDEE
Your BMR alone isn’t sufficient for planning your diet. Multiply it by your activity factor:
| Activity Level | Factor | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little exercise |
| Lightly active | 1.375 | Light exercise 1-3 days/week |
| Moderately active | 1.55 | Moderate exercise 3-5 days/week |
| Very active | 1.725 | Intense exercise 6-7 days/week |
| Extra active | 1.9 | Athlete, intense physical work |
Practical Application
30-year-old woman with BMR of 1,320 kcal:
- Sedentary: 1,320 x 1.2 = 1,584 kcal/day
- Moderately active: 1,320 x 1.55 = 2,046 kcal/day
- Very active: 1,320 x 1.725 = 2,277 kcal/day
Calculation Limitations
Formulas provide estimates. Your actual BMR may vary by 10-15% depending on:
- Your genetics
- Your body composition
- Your dieting history
- Certain medical conditions (thyroid, etc.)
The best approach is to use the calculation as a starting point, then adjust based on your actual results over 2-4 weeks.
Track Your Calories with Voical
Once your calorie goal is defined, Voical helps you stick to it. Photograph your meals, the AI calculates calories, and you stay in control effortlessly.