BMR Calculator - Calculate Basal Metabolic Rate
Calculate your Basal Metabolic Rate (BMR) using scientifically validated formulas to determine daily calorie needs at rest for optimal weight management and nutrition planning
BMR Calculator
Your Results
What is a BMR Calculator?
A BMR Calculator is a free health tool that calculates your Basal Metabolic Rate - the number of calories your body burns at complete rest. It uses scientifically validated formulas like Mifflin-St Jeor and Harris-Benedict to determine your minimum daily calorie needs based on age, gender, weight, and height.
This calculator helps you:
- Determine resting calorie burn - Know your baseline metabolism
- Plan nutrition goals - Set accurate calorie targets for weight loss or gain
- Calculate activity needs - See total daily calories by activity level
- Manage weight effectively - Create sustainable diet plans based on science
To calculate your total daily calorie needs including activity, check out our TDEE Calculator to determine your Total Daily Energy Expenditure based on your lifestyle and exercise habits.
For planning your daily nutrition breakdown, explore our Macronutrient Calculator to calculate optimal protein, carbs, and fats based on your calorie needs and fitness goals.
To create a calorie deficit for weight loss, use our Calorie Deficit Calculator to determine how many calories below your BMR you should eat to reach your target weight safely.
For understanding your body composition beyond just calories, try our Body Fat Percentage Calculator to measure what percentage of your weight is fat versus lean mass.
To determine your ideal target weight for optimal health, check our Ideal Body Weight Calculator to set realistic weight goals based on your height and body frame.
How the BMR Calculator Works
The calculator uses two scientifically validated formulas:
Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161
Men: 88.362 + (13.397 × weight kg) + (4.799 × height cm) - (5.677 × age)
Women: 447.593 + (9.247 × weight kg) + (3.098 × height cm) - (4.330 × age)
Activity Level Multipliers:
- Sedentary (1.2): Little or no exercise
- Light (1.375): Exercise 1-3 days/week
- Moderate (1.55): Exercise 3-5 days/week
- Active (1.725): Exercise 6-7 days/week
- Very Active (1.9): Physical job or 2x/day training
Your TDEE = BMR × Activity Multiplier
Understanding BMR and Metabolism
BMR vs RMR
BMR and RMR (Resting Metabolic Rate) are nearly identical. RMR is slightly higher as it's measured under less restrictive conditions.
Muscle Mass Impact
More muscle increases BMR. Muscle burns 6 cal/lb/day at rest vs 2 cal/lb/day for fat tissue.
Age Factor
BMR decreases with age due to muscle loss and metabolic slowdown, about 2-3% per decade after age 30.
Gender Difference
Men typically have 5-10% higher BMR due to greater muscle mass and body size.
How to Use This Calculator
Select Gender
Choose male or female for accurate formula
Choose Units
Select metric (kg/cm) or imperial (lbs/ft)
Enter Details
Input age, weight, and height accurately
View Results
See BMR and activity-based calorie needs
Benefits of Knowing Your BMR
- • Accurate Calorie Planning: Know your exact baseline calorie needs for effective diet planning and weight management.
- • Weight Management: Create sustainable calorie deficits or surpluses based on scientifically validated goals.
- • Metabolic Awareness: Understand how your body burns calories at rest and identify factors affecting metabolism.
- • Activity Adjustment: See how exercise impacts your total calorie needs and adjust nutrition accordingly.
- • Nutrition Optimization: Set macronutrient targets based on accurate calorie needs for optimal health and performance.
Factors That Affect Your BMR
1. Body Composition
Higher muscle mass increases BMR significantly. Athletes may have 5-10% higher BMR than the equation predicts due to increased lean body mass.
2. Genetics
Some people naturally have faster or slower metabolisms due to genetic factors affecting thyroid function and cellular efficiency.
3. Hormones
Thyroid function, cortisol levels, testosterone, and other hormones significantly impact metabolic rate and calorie burn.
4. Diet History
Chronic dieting can lower BMR by 10-20% through metabolic adaptation. Regular eating patterns help maintain healthy metabolism.
Frequently Asked Questions (FAQ)
Q: What is BMR (Basal Metabolic Rate)?
A: BMR is the number of calories your body burns at complete rest to maintain essential physiological functions like breathing, circulation, cell production, and nutrient processing. It represents your minimum daily calorie requirement to stay alive.
Q: How is BMR calculated?
A: BMR is calculated using scientifically validated formulas. The Mifflin-St Jeor equation (most accurate): Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5. Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161. The Harris-Benedict equation is also commonly used.
Q: Should I eat only my BMR calories?
A: No, BMR is your resting calorie burn. You need to multiply it by your activity level (1.2-1.9) to get your total daily calorie needs (TDEE). Eating only BMR calories would be too low for most people and could slow metabolism.
Q: Can I increase my BMR?
A: Yes, building muscle through strength training increases BMR. Each pound of muscle burns about 6 calories per day at rest, compared to 2 calories for fat. Regular exercise, adequate protein intake, and avoiding extreme calorie restriction also help maintain healthy BMR.
Q: What's the difference between BMR and TDEE?
A: BMR is your resting calorie burn, while TDEE (Total Daily Energy Expenditure) includes calories burned through all activities. TDEE = BMR × activity multiplier (1.2-1.9). BMR accounts for 60-75% of total daily calories burned.
Q: Which BMR formula is most accurate?
A: The Mifflin-St Jeor equation (1990) is considered most accurate for modern populations, with ±10% accuracy. It replaced the Harris-Benedict equation as the gold standard. The Katch-McArdle formula is best if you know your body fat percentage.
Q: Why is my BMR different from my friend's?
A: BMR varies based on age, gender, weight, height, muscle mass, genetics, and hormones. Men typically have higher BMR due to more muscle mass. Younger people and those with more muscle burn more calories at rest.
Q: How accurate is the BMR calculator?
A: The Mifflin-St Jeor equation is accurate within ±10% for most people. Factors like muscle mass, genetics, and metabolic conditions can affect accuracy. It's a reliable starting point for calorie planning, but individual results may vary.