BMR Calculator
Calculate your Basal Metabolic Rate (BMR) – the calories your body needs at complete rest.
Your Information
Your BMR Results
This is what your body burns at complete rest
Based on sedentary activity level
• Use the “Moderately Active” number if you exercise 3-5 days per week
• Track your food intake for 1-2 weeks to compare with these estimates
• Adjust ±100 calories every 2-3 weeks based on progress
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BMR Reference Table
Typical BMR values for different body types (using Mifflin-St Jeor equation):
| Profile | Age | Height | Weight | BMR (calories) |
|---|---|---|---|---|
| Average Male | 30 | 5’9″ (175 cm) | 160 lbs (72.5 kg) | 1,674 |
| Average Female | 30 | 5’4″ (163 cm) | 140 lbs (63.5 kg) | 1,386 |
| Tall Male | 25 | 6’2″ (188 cm) | 180 lbs (81.6 kg) | 1,884 |
| Petite Female | 35 | 5’1″ (155 cm) | 120 lbs (54.4 kg) | 1,248 |
Note: These are BMR values only. Add activity multiplier for total daily calories.
Common BMR Calculation Mistakes
- • Confusing BMR with TDEE: BMR is calories at complete rest. TDEE includes activity. Multiply BMR by activity factor for total daily needs.
- • Using wrong formula: The Mifflin-St Jeor equation (used here) is most accurate for general population. Harris-Benedict is older and less accurate.
- • Overestimating activity level: Most office workers are “sedentary” or “lightly active,” not “moderately active.” Be honest about your daily movement.
- • Not accounting for age: BMR decreases about 1-2% per decade after 20. A 50-year-old needs fewer calories than a 30-year-old with same stats.
- • Forgetting about body composition: Muscle burns more calories than fat at rest. Two people with same weight but different muscle mass have different BMRs.
How BMR Calculation Works
Basal Metabolic Rate (BMR) represents the number of calories your body needs to perform basic life-sustaining functions while at complete rest. These functions include breathing, circulation, cell production, nutrient processing, protein synthesis, and ion transport.
Mifflin-St Jeor Equation
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
This formula, developed in 1990, is considered the most accurate for estimating BMR in the general population. It accounts for age, height, weight, and gender differences in metabolism.
For example, a 30-year-old man who is 5’9″ (175 cm) and weighs 160 lbs (72.5 kg) would calculate:
BMR = (10 × 72.5) + (6.25 × 175) – (5 × 30) + 5 = 1,674 calories/day
BMR vs. TDEE: Understanding the Difference
BMR is often confused with Total Daily Energy Expenditure (TDEE). Here’s the distinction:
| Term | Definition | Typical Percentage |
|---|---|---|
| BMR | Calories burned at complete rest | 60-75% of TDEE |
| TEF | Thermic Effect of Food (digestion) | 10% of TDEE |
| NEAT | Non-Exercise Activity Thermogenesis | 15% of TDEE |
| Exercise | Intentional exercise calories | 0-30% of TDEE |
| TDEE | Total Daily Energy Expenditure | BMR + TEF + NEAT + Exercise |
To calculate your total calorie needs, multiply your BMR by an activity factor:
Activity Multipliers
Sedentary (little or no exercise): BMR × 1.2
Lightly active (light exercise 1-3 days/week): BMR × 1.375
Moderately active (moderate exercise 3-5 days/week): BMR × 1.55
Very active (hard exercise 6-7 days/week): BMR × 1.725
Extremely active (very hard exercise & physical job): BMR × 1.9
Factors That Affect BMR
Several factors influence your basal metabolic rate:
- Muscle mass: Muscle tissue burns more calories at rest than fat tissue. Each pound of muscle burns about 6 calories per day at rest.
- Age: Metabolism slows about 1-2% per decade after age 20 due to muscle loss and hormonal changes.
- Gender: Men typically have higher BMRs due to greater muscle mass and larger body size.
- Body size: Larger bodies have higher BMRs. This includes both height and weight.
- Genetics: Some people inherit faster or slower metabolisms.
- Thyroid function: Thyroid hormones regulate metabolism. Overactive thyroid increases BMR, underactive decreases it.
- Body temperature: Fever or exposure to cold can increase BMR.
- Pregnancy: BMR increases during pregnancy to support fetal growth.
The Muscle Metabolism Advantage
Building muscle is one of the few ways to permanently increase your BMR. While cardio burns calories during exercise, strength training builds muscle that burns calories 24/7. A 5-pound muscle gain can increase daily BMR by 30-50 calories.
Using BMR for Weight Management
BMR provides the foundation for all weight management calculations:
To maintain weight: Eat at your TDEE (BMR × activity factor)
To lose weight: Eat below your TDEE (typically 250-500 calories less)
To gain weight: Eat above your TDEE (typically 250-500 calories more)
One pound of body fat contains approximately 3,500 calories. Therefore:
- 500 calorie daily deficit = 1 pound loss per week
- 250 calorie daily deficit = 0.5 pound loss per week
- 250 calorie daily surplus = 0.5 pound gain per week
- 500 calorie daily surplus = 1 pound gain per week
Frequently Asked Questions
How accurate is the BMR calculation?
The Mifflin-St Jeor equation is accurate within ±5% for about 80% of the population. Individual variations in muscle mass, genetics, and medical conditions can affect actual BMR. Use the calculation as a starting point and adjust based on results.
Why is my BMR different from my friend with similar stats?
Body composition differences are the main reason. More muscle mass means higher BMR. Other factors include thyroid function, stress levels, sleep quality, and genetic variations in metabolism.
Can I increase my BMR?
Yes, through strength training to build muscle, adequate protein intake to support muscle, proper hydration, quality sleep, and managing stress. Extreme calorie restriction can lower BMR as the body adapts to conserve energy.
How often should I recalculate my BMR?
Recalculate every 10-15 pounds of weight change, or if your activity level changes significantly. Also recalculate every year as you age, since BMR decreases about 1-2% per decade after age 20.
What’s the difference between BMR and RMR?
Resting Metabolic Rate (RMR) is similar to BMR but measured under less strict conditions. BMR requires complete rest in a fasted state, while RMR allows for some basic activity. In practice, the terms are often used interchangeably, and the difference is usually less than 10%.
Why does BMR matter for weight loss?
BMR represents the majority of calories you burn each day (60-75%). Knowing your BMR helps create an appropriate calorie deficit for weight loss without slowing your metabolism too much. Too large a deficit can cause muscle loss and metabolic adaptation.
Practical BMR Examples
Example 1: College student trying to lose weight
Emma is 20, female, 5’6″, 150 lbs. Her BMR is 1,450 calories. As a moderately active student (BMR × 1.55), her TDEE is 2,248 calories. To lose 1 pound per week, she aims for 1,748 calories daily (500 calorie deficit from TDEE).
Example 2: Office worker maintaining weight
David is 45, male, 5’11”, 190 lbs. His BMR is 1,758 calories. With a sedentary job (BMR × 1.2), his TDEE is 2,110 calories. He eats at this level to maintain his weight, focusing on protein and vegetables for nutrient density.
Example 3: Athlete building muscle
Marcus is 25, male, 6’0″, 180 lbs. His BMR is 1,844 calories. As a very active athlete (BMR × 1.725), his TDEE is 3,181 calories. To gain 0.5 pounds per week, he eats 3,431 calories daily with emphasis on protein and timing carbs around workouts.
Special Considerations
For very overweight individuals: BMR calculations may overestimate needs because they assume average body composition. As weight loss occurs, recalculate frequently since BMR decreases with weight loss.
For older adults: Age-related muscle loss (sarcopenia) decreases BMR. Strength training becomes crucial to preserve metabolism. Calorie needs may be 10-20% lower than for younger adults with similar stats.
For athletes: High muscle mass increases BMR. The standard activity multipliers may underestimate needs for extremely active individuals who train multiple hours daily.
Metabolic Adaptation Warning
When you consistently eat below your BMR for extended periods, your body may lower its metabolic rate to conserve energy. This “starvation mode” adaptation makes continued weight loss difficult. To prevent this, don’t eat below your BMR for more than short periods, include refeed days, and focus on strength training to preserve muscle.
Comparing BMR Formulas
| Formula | Year | Accuracy | Best For |
|---|---|---|---|
| Mifflin-St Jeor | 1990 | Most accurate (±5%) | General population |
| Harris-Benedict | 1919 | Less accurate (±10-15%) | Historical reference |
| Katch-McArdle | 1996 | Very accurate if body fat known | Athletes, known body fat % |
The Katch-McArdle formula requires body fat percentage: BMR = 370 + (21.6 × lean body mass in kg). This is more accurate for athletes but requires knowing your body fat percentage.
Tips for Metabolic Health
- Eat enough protein: 0.7-1 gram per pound of body weight helps preserve muscle
- Strength train 2-3 times weekly: Builds muscle that burns calories 24/7
- Stay hydrated: Dehydration can temporarily lower metabolism
- Prioritize sleep: Poor sleep disrupts hunger hormones and metabolism
- Manage stress: Chronic stress increases cortisol, which can affect metabolism
- Don’t skip meals: Regular eating helps maintain stable blood sugar and metabolism
- Include refeed days: Occasionally eating at maintenance calories can prevent metabolic adaptation during weight loss
When to Consult a Professional
If you’re consistently eating below your calculated needs and not losing weight, or if you have symptoms like extreme fatigue, hair loss, or temperature intolerance, consult a healthcare provider. These could indicate thyroid issues or other metabolic conditions.
Remember: BMR is a starting point, not a fixed number. Use it to create an initial calorie target, track your progress for 3-4 weeks, then adjust based on results. Sustainable changes to diet and exercise habits matter more than precise calorie counting in the long term.