BMR Calculator
Calculate your Basal Metabolic Rate and understand the energy your body needs at complete rest.
BMR Calculator
Your Basal Metabolic Rate (BMR)
1,618 calories/day
Based on the Mifflin-St Jeor formula
BMR by Different Formulas
Mifflin-St Jeor
1,618 cal
Most accurate for general population
Harris-Benedict
1,672 cal
Classic formula (1919, revised 1984)
Katch-McArdle
1,580 cal
Best when body fat % is known
Calories Burned by Activity Level
Sleep
64 cal/hr
Sleeping, resting in bed
Sedentary
88 cal/hr
Sitting, reading, watching TV
Light
168 cal/hr
Walking slowly, light chores
Moderate
337 cal/hr
Fast walking, cycling, dancing
Intense
539 cal/hr
Running, HIIT, sports
What Does Your BMR Mean?
Your BMR of 1,618 calories represents the minimum energy your body needs to function at rest. This includes breathing, circulation, cell production, and maintaining body temperature.
Important: BMR alone doesn't account for the calories you need for daily activities. To determine your total daily energy needs (TDEE), you must factor in your activity level.
Note: These calculations provide estimates based on standard formulas and may vary based on individual factors. Consult with a healthcare professional or registered dietitian for personalized advice.
Understanding Basal Metabolic Rate
Basal Metabolic Rate (BMR) represents the minimum amount of energy your body requires to perform essential functions while at complete rest. These functions include breathing, blood circulation, cell production, nutrient processing, and maintaining body temperature.
Key Facts About BMR
- Accounts for 60-70% of your total daily energy expenditure
- Remains relatively constant throughout the day (unlike physical activity energy)
- Is measured under very specific conditions: lying down at complete rest, in a temperate environment, after 8 hours of sleep, and while fasting
- Is sometimes used interchangeably with RMR (Resting Metabolic Rate), though RMR is slightly higher (about 10%)
- Cannot be directly changed in a significant way through short-term interventions
Factors Affecting Your BMR
Factors That Increase BMR
- Greater muscle mass
- Regular exercise (particularly strength training)
- Taller height
- Male biological sex (typically)
- Younger age (metabolism slows with age)
- Stress and anxiety
- Pregnancy
- Fever or illness
- Certain medications (e.g., caffeine, nicotine)
- Thyroid disorders (hyperthyroidism)
Factors That Decrease BMR
- Higher body fat percentage
- Severe calorie restriction (metabolic adaptation)
- Aging
- Dehydration
- Poor sleep quality
- Thyroid disorders (hypothyroidism)
- Malnutrition
- Loss of muscle mass
- Female biological sex (typically)
- Extreme dieting history ("yo-yo dieting")
Why BMR Matters for Health
Understanding your BMR provides valuable insights into your body's energy needs and can help with:
Weight Management
BMR forms the foundation of your calorie needs. Knowing this baseline helps create appropriate calorie targets for weight loss, maintenance, or gain.
Metabolic Health
An abnormally high or low BMR may indicate underlying health issues such as thyroid dysfunction, which can be addressed with proper medical care.
Body Composition
Building and maintaining muscle mass helps support a higher BMR, contributing to better metabolic health and body composition over time.
The Science Behind BMR Formulas
Several equations have been developed to estimate BMR. Each formula has its strengths and is best suited for different populations. Our calculator offers three widely-used formulas:
Mifflin-St Jeor Equation (1990)
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
Best for: Most accurate for the general population. Studies have found it to be the most reliable formula for non-athletic adults.
Harris-Benedict Equation (Revised 1984)
For men:
BMR = 13.397 × weight(kg) + 4.799 × height(cm) - 5.677 × age(years) + 88.362
For women:
BMR = 9.247 × weight(kg) + 3.098 × height(cm) - 4.330 × age(years) + 447.593
Best for: Historical comparisons and research contexts. This is the oldest formula, originally created in 1919 and revised in 1984. It tends to slightly overestimate BMR in most modern populations.
Katch-McArdle Formula
For all genders:
BMR = 370 + (21.6 × Lean Body Mass in kg)
where Lean Body Mass = Weight in kg × (1 - (Body Fat % ÷ 100))
Best for: Athletes, bodybuilders, and individuals who know their body fat percentage. This formula accounts for the metabolic differences between lean tissue and fat tissue, making it potentially more accurate for those with body compositions that differ from average.
Which Formula Should You Use?
For most people, the Mifflin-St Jeor equation provides the most accurate estimate. If you know your body fat percentage and have an athletic build, the Katch-McArdle formula may give you a more precise result. The Harris-Benedict equation is included primarily for comparison and historical context.
Strategies to Support a Healthy Metabolism
While BMR is largely determined by factors like age, gender, and genetics, there are several evidence-based strategies that can help support a healthy metabolism:
Build and Preserve Muscle Mass
Muscle tissue is metabolically active and burns more calories at rest than fat tissue. Prioritizing muscle preservation and growth can help maintain a higher BMR.
- Engage in resistance training 2-3 times per week
- Consume adequate protein (1.6-2.2g per kg of bodyweight for building muscle)
- Avoid extreme calorie deficits that can lead to muscle loss
- Include all major muscle groups in your training program
Optimize Nutrition
Your diet provides the energy and nutrients necessary for metabolic processes. Proper nutrition helps support optimal metabolic function.
- Eat sufficient calories to support bodily functions
- Stay hydrated as dehydration can temporarily lower BMR
- Include protein with each meal to support muscle maintenance
- Consume adequate micronutrients, especially B vitamins, iron, and magnesium
- Avoid extended fasting periods that may signal energy scarcity to your body
Prioritize Sleep and Recovery
Poor sleep quality and chronic stress can negatively impact metabolic health and reduce BMR over time.
- Aim for 7-9 hours of quality sleep each night
- Maintain a consistent sleep schedule to support circadian rhythms
- Manage stress through meditation, breathing exercises, or other techniques
- Allow adequate recovery between intense workouts
Be Mindful of Age-Related Changes
BMR naturally decreases with age, but certain strategies can help mitigate this decline.
- Increase protein intake as you age to combat sarcopenia (age-related muscle loss)
- Maintain regular resistance training throughout life
- Stay physically active daily, even if just through walking and light movement
- Have regular thyroid function checks after age 50
- Adjust calorie intake to match changing metabolic needs
Important Considerations
Remember that BMR is just one component of your overall energy expenditure. For weight management and health optimization, you should also consider:
- Non-Exercise Activity Thermogenesis (NEAT) - energy expended through daily movement like walking, fidgeting, and standing
- Exercise Activity Thermogenesis (EAT) - energy expended during intentional exercise
- Thermic Effect of Food (TEF) - energy required to digest and process food
These components, combined with your BMR, make up your Total Daily Energy Expenditure (TDEE).
Frequently Asked Questions
What's the difference between BMR and RMR?
BMR (Basal Metabolic Rate) measures calories burned in a completely rested state under very specific conditions (lying down, after 8 hours of sleep, in a fasting state, in a temperature-controlled environment). RMR (Resting Metabolic Rate) is slightly less restrictive and typically measured under more practical conditions. RMR is usually about 10% higher than BMR. For practical purposes, the terms are often used interchangeably, though they're technically different.
Is a higher BMR better for weight loss?
A higher BMR means your body burns more calories at rest, which can make weight management easier. However, having a high or low BMR isn't inherently "good" or "bad" - it's simply a characteristic of your body. What matters most is understanding your personal BMR and adjusting your nutrition and activity accordingly. That said, building muscle through resistance training is a healthy way to support a slightly higher BMR over time.
Can I increase my BMR significantly?
While you can't dramatically change your BMR in the short term, you can make modest improvements through building muscle mass (which burns more calories at rest than fat tissue), avoiding extreme calorie restriction that triggers metabolic adaptation, staying properly hydrated, and ensuring adequate sleep. Most people can expect to increase their BMR by about 5-10% through significant muscle gain, which may take months or years of consistent training.
Does metabolism really slow with age?
Yes, metabolism does typically slow with age, but recent research suggests the decline is not as dramatic as once thought. BMR decreases approximately 1-2% per decade after age 20, primarily due to loss of muscle mass (sarcopenia) and hormonal changes. However, maintaining muscle through resistance training and proper nutrition can significantly minimize this decline. Many age-related metabolic changes are actually due to lifestyle factors like decreased activity, rather than aging itself.
How accurate are BMR calculators?
BMR calculators provide estimates based on equations derived from population studies. They're typically accurate within 10-15% for most people. For the highest accuracy, the Mifflin-St Jeor equation is recommended for the general population, while the Katch-McArdle formula may be better for athletic individuals (if you know your body fat percentage). The gold standard for measuring BMR is direct or indirect calorimetry in a clinical setting, but these methods are expensive and not readily accessible.
Related Calculators
Disclaimer: This BMR calculator provides estimates based on mathematical formulas and should not be considered medical advice. These calculations may not be accurate for everyone, particularly individuals with certain medical conditions or those outside typical body composition ranges. Consult with healthcare professionals before making significant changes to your diet or exercise routine.