Free to Use

BMR Calculator

Calculate your Basal Metabolic Rate and Total Daily Energy Expenditure using multiple validated formulas. Get personalized metabolism analysis and nutrition recommendations

Factors Affecting Your BMR

Age
BMR decreases by 1-2% per decade after age 30
Loss of muscle mass and decreased organ function contribute to metabolic slowdown. Resistance training can help maintain BMR.
Gender
Men typically have 10-15% higher BMR than women
Due to larger body size, higher muscle mass, and hormonal differences. Testosterone promotes muscle development.
Body Composition
Muscle tissue burns 3x more calories than fat tissue
Increasing muscle mass through resistance training can significantly boost BMR. Each pound of muscle burns ~6 calories/day at rest.
Genetics
Can vary BMR by ±200-300 calories between individuals
Some people are naturally "fast" or "slow" metabolizers. However, lifestyle factors can override genetic predisposition.
Thyroid Function
Regulates metabolic rate through hormone production
Hyperthyroidism increases BMR, hypothyroidism decreases it. Regular check-ups can detect thyroid issues early.
Climate
Extreme temperatures can increase BMR by 5-10%
Body works harder to maintain core temperature in very hot or cold environments. Seasonal variations are normal.
Medications
Some drugs can increase or decrease metabolic rate
Stimulants may increase BMR, while some antidepressants and beta-blockers may decrease it. Consult your doctor if concerned.
Sleep Quality
Poor sleep can reduce BMR by 2-5%
Inadequate sleep affects hormones that regulate metabolism. Aim for 7-9 hours of quality sleep nightly.
Stress Levels
Chronic stress can lower BMR over time
Elevated cortisol from chronic stress can slow metabolism. Stress management techniques can help maintain healthy BMR.
Dieting History
Severe calorie restriction can reduce BMR by 10-40%
Metabolic adaptation occurs with extreme dieting. Gradual weight loss and refeed periods help maintain BMR.

Boosting Your BMR

Strength Training

Build and maintain muscle mass through resistance exercise. Each pound of muscle burns significantly more calories than fat tissue, even at rest.

Protein Intake

Protein has the highest thermic effect of food (20-30%). Eating adequate protein can increase daily energy expenditure.

Stay Hydrated

Proper hydration supports optimal metabolic function. Drinking cold water may temporarily boost metabolism through thermogenesis.

Get Quality Sleep

Prioritize 7-9 hours of quality sleep to maintain healthy hormone levels and metabolic function.

Manage Stress

Chronic stress can slow metabolism. Practice stress-reduction techniques like meditation, yoga, or regular exercise.

Don't Over-Restrict Calories

Extreme calorie restriction can cause metabolic adaptation. Aim for moderate, sustainable calorie deficits for weight loss.

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Multiple BMR Formulas
Compare results from Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas for the most accurate estimate.
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TDEE Calculation
Calculate Total Daily Energy Expenditure with detailed breakdown of energy expenditure components.
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Macro Calculator
Get personalized macronutrient recommendations based on your goals, activity level, and calorie needs.
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Metabolic Age
Assess your metabolic health by comparing your BMR to others of different ages with similar characteristics.
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Factor Analysis
Understand the 10 key factors that affect your BMR and learn how to optimize your metabolism.
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Multiple Units
Supports both metric (kg/cm) and imperial (lbs/ft) units for global accessibility.

Understanding Basal Metabolic Rate (BMR)

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions while at complete rest. It represents the minimum energy requirement for vital processes such as breathing, circulation, cellular production, and organ function.

BMR vs RMR vs TDEE

BMR = Energy for basic functions at complete rest
Measured under strict laboratory conditions after 12-hour fast
RMR = Resting Metabolic Rate (slightly higher than BMR)
More practical measurement, typically 10-20% higher than BMR
TDEE = BMR × Activity Factor
Total Daily Energy Expenditure including all activities

BMR Calculation Formulas

Mifflin-St Jeor (Recommended)

Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161
Most accurate for general population.

Harris-Benedict (Revised)

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)
Older formula, may overestimate by 5%.

Katch-McArdle

Both: 370 + (21.6 × lean body mass kg)
Most accurate when body fat percentage is known. Requires lean body mass calculation.

Components of Daily Energy Expenditure

BMR/RMR (60-75%)

Largest component of energy expenditure. Includes brain function, heart beating, breathing, and cellular maintenance.

Thermic Effect of Food (8-15%)

Energy cost of digesting, absorbing, transporting, and storing nutrients. Protein has highest thermic effect.

Exercise Activity (15-30%)

Planned physical activity including sports, gym workouts, and structured exercise sessions.

NEAT (15-30%)

Non-Exercise Activity Thermogenesis. Includes fidgeting, maintaining posture, and daily activities.

BMR and Health Implications

Factors That Increase BMR

Higher Muscle Mass

Muscle tissue is metabolically active, burning 3 times more calories than fat tissue even at rest.

Youth

Younger individuals typically have higher BMR due to rapid cell turnover and growth processes.

Male Gender

Men typically have 10-15% higher BMR due to larger body size and higher muscle-to-fat ratio.

Larger Body Size

Bigger bodies require more energy to maintain basic functions, resulting in higher absolute BMR.

Hyperthyroidism

Overactive thyroid increases metabolic rate significantly, sometimes by 20-30% above normal.

Fever/Illness

Body temperature increases of 1°F can raise BMR by approximately 7% as immune system works harder.

Factors That Decrease BMR

Aging

BMR decreases by 1-2% per decade after age 30, primarily due to muscle loss and decreased organ function.

Calorie Restriction

Severe or prolonged calorie restriction can reduce BMR by 10-40% as body adapts to conserve energy.

Hypothyroidism

Underactive thyroid can reduce BMR by 15-20%, leading to fatigue and weight gain.

Loss of Muscle Mass

Sedentary lifestyle and aging lead to muscle loss, reducing the body's calorie-burning capacity.

Poor Sleep

Chronic sleep deprivation can reduce BMR by 2-5% and negatively affect metabolic hormones.

Chronic Stress

Prolonged stress elevates cortisol, which can slow metabolism and promote fat storage.

Optimizing Your BMR

Resistance Training

Build and maintain muscle mass with strength training 2-3 times per week. Focus on compound movements.

Adequate Protein

Consume 1.6-2.2g protein per kg body weight. Protein has high thermic effect and preserves muscle mass.

Stay Active

Increase NEAT through walking, taking stairs, standing desks, and maintaining an active lifestyle.

Quality Sleep

Prioritize 7-9 hours of quality sleep to maintain optimal hormone function and metabolic health.

Manage Stress

Practice stress-reduction techniques to maintain healthy cortisol levels and metabolic function.

Avoid Extreme Diets

Maintain moderate calorie deficits (300-500 calories) to prevent metabolic adaptation during weight loss.

How to Use Our BMR Calculators

BMR Calculator

Calculate your Basal Metabolic Rate using multiple validated formulas:

  1. Select units: Choose between metric or imperial measurements
  2. Enter demographics: Gender, age, weight, and height are required
  3. Add body fat (optional): If known, enables Katch-McArdle calculation
  4. Compare results: Review different formulas to understand your BMR range
  5. Use recommended value: Based on most current research for accuracy

TDEE Calculator

Determine your total daily energy expenditure:

  1. Calculate BMR first: Input same demographic information
  2. Select activity level: Be honest about your actual activity level
  3. Review TDEE breakdown: Understand how much energy each component uses
  4. Apply to goals: Use TDEE for weight management and nutrition planning

Macro Calculator

Get personalized macronutrient recommendations:

  1. Set calorie target: Use TDEE result or specific calorie goal
  2. Choose goal: Weight loss, maintenance, muscle gain, or athletic performance
  3. Input activity level: Affects protein and carbohydrate recommendations
  4. Review macros: Get specific gram targets for protein, carbs, and fat

Metabolic Age Calculator

Assess your metabolic health relative to others:

  1. Provide complete data: More information improves accuracy
  2. Include body fat if known: Significantly improves assessment precision
  3. Be honest about activity: Affects metabolic age calculation
  4. Interpret results: Understand what metabolic age means for your health

Frequently Asked Questions (FAQ)

How accurate are BMR calculator predictions?
BMR calculators using validated formulas are typically accurate within ±10-15% for most people. The Mifflin-St Jeor equation is most accurate for the general population, while Katch-McArdle is most precise when body fat percentage is known. Individual variations due to genetics, medical conditions, and other factors can affect accuracy.
Which BMR formula should I use?
For most people, the Mifflin-St Jeor equation provides the most accurate results. Use Harris-Benedict if you want a second opinion, but it may overestimate by 5%. If you know your body fat percentage, Katch-McArdle is most accurate as it considers lean body mass. Our calculator shows all three for comparison.
What's the difference between BMR and TDEE?
BMR is your baseline calorie needs at complete rest, while TDEE (Total Daily Energy Expenditure) includes all activities. TDEE = BMR × activity factor. BMR typically accounts for 60-75% of total daily calories, with the remainder from activity, food digestion, and movement.
Why does my BMR decrease with age?
BMR naturally decreases by 1-2% per decade after age 30 due to several factors: loss of muscle mass, decreased organ function, hormonal changes, and reduced cellular activity. However, maintaining muscle through resistance training and staying active can significantly slow this decline.
Can I increase my BMR?
Yes! The most effective way is building muscle through resistance training, as muscle tissue burns more calories than fat. Other strategies include: eating adequate protein, staying hydrated, getting quality sleep, managing stress, and avoiding extreme calorie restriction which can slow metabolism.
How do I choose the right activity level for TDEE?
Be conservative and honest about your actual activity level. Sedentary = desk job with little exercise; Lightly active = light exercise 1-3 days/week; Moderately active = moderate exercise 3-5 days/week; Very active = hard exercise 6-7 days/week; Extremely active = very hard exercise plus physical job.
What is metabolic age and does it matter?
Metabolic age compares your BMR to the average BMR of different age groups. If your metabolic age is lower than your actual age, your metabolism is more efficient than average. While not a perfect health indicator, it can provide insight into your metabolic health and the effectiveness of your lifestyle choices.
Can medical conditions affect my BMR?
Yes, several conditions can significantly affect BMR. Thyroid disorders (hyper/hypothyroidism) can increase or decrease BMR by 15-30%. Diabetes, PCOS, certain medications, and metabolic disorders can also impact BMR. If you suspect a medical condition is affecting your metabolism, consult a healthcare provider.
How does dieting affect BMR?
Severe or prolonged calorie restriction can reduce BMR by 10-40% through metabolic adaptation. This is why extreme diets often fail long-term. To minimize BMR reduction during weight loss: maintain moderate deficits (300-500 calories), eat adequate protein, include resistance training, and consider diet breaks.
Should I eat exactly my BMR calories?
No, never eat only your BMR calories as this would be dangerously low. Your BMR is the minimum energy needed for survival. For weight maintenance, eat around your TDEE. For weight loss, create a moderate deficit from TDEE (300-500 calories). Eating below BMR can trigger metabolic adaptation and is unsafe.

About Our BMR Calculator

Our comprehensive BMR calculator suite provides scientifically-validated calculations for Basal Metabolic Rate, Total Daily Energy Expenditure, and metabolic analysis. Built using peer-reviewed formulas from nutrition and exercise science research.

Why Choose Our BMR Calculator?

Multiple Validated Formulas

Compare results from Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle equations for the most accurate estimate.

Comprehensive Analysis

Five different calculators covering BMR, TDEE, macronutrients, metabolic age, and factor analysis.

Evidence-Based

Uses formulas and recommendations from peer-reviewed research in nutrition and exercise science.

Educational Focus

Explains metabolic concepts, factors affecting BMR, and optimization strategies for better understanding.

Personalized Results

Accounts for age, gender, body composition, and activity level for individualized recommendations.

Privacy Protected

All calculations performed locally in your browser. No personal health data stored or transmitted.

Health Disclaimer: This BMR calculator is for educational and nutritional planning purposes only. It should not replace professional medical advice or metabolic testing. Individual metabolic rates can vary significantly due to genetics, medical conditions, medications, and other factors. If you have health conditions affecting metabolism or are taking medications, consult qualified healthcare providers for personalized guidance.