BMR Calculator
Free Basal Metabolic Rate Calculator. Calculate the Calories Your Body Burns at Rest Each Day.
Use our free BMR calculator to determine your Basal Metabolic Rate - the number of calories your body burns at rest just to maintain essential functions like breathing, circulation, and cell production. Enter your unique inputs to receive your personalized BMR calculation. Our calculator works for both men and women, with imperial (pounds/feet) and metric (kilograms/centimeters) options available for your convenience.
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What is BMR?
Basal Metabolic Rate
Your Basal Metabolic Rate, or BMR, is the number of calories your body burns at complete rest to maintain essential life-sustaining functions. These vital functions include breathing, blood circulation, cell production and repair, hormone regulation, and maintaining body temperature. Your BMR represents the minimum amount of energy your body requires to keep you alive if you were to rest in bed for 24 hours without moving.
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BMR is often referred to as your "resting metabolism" and typically accounts for 60-75% of your total daily calorie expenditure. This means that most of the calories you burn each day come from simply keeping your body functioning, not from physical activity or exercise. Understanding your BMR can provide valuable insight into your body's baseline energy needs and help you make informed decisions about nutrition and calorie intake.
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Your individual BMR is influenced by several factors including your age, gender, height, weight, and body composition. Two people of the same weight may have different BMRs based on these variables, which is why personalized calculations using validated formulas can provide more accurate estimates than general guidelines.
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Knowing your BMR can support better health decisions by helping you understand how many calories your body needs at minimum to function properly. This knowledge becomes particularly useful when planning nutrition strategies, managing weight, or working with healthcare professionals to address metabolic health. Your BMR serves as the foundation for calculating your total daily calorie needs and creating a sustainable approach to nutrition.
The Purpose of a BMR Calculator
A BMR calculator estimates your Basal Metabolic Rate using validated formulas based on your height, weight, age, and gender. The primary purpose is to help you understand the approximate number of calories your body may need at rest to maintain basic physiological functions. This information can serve as a starting point for making informed decisions about daily calorie intake, whether you're working with a healthcare provider on metabolic health or wanting to better understand your body's baseline energy requirements.
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Our BMR calculator uses the Mifflin-St Jeor equation, which research suggests may provide reasonable estimates of basal metabolic rate for many individuals. The calculator accounts for the physiological differences between men and women, as well as how age and body size can influence metabolic rate. Individual results may vary, and BMR calculators provide only estimates of your actual metabolic rate.
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It's important to note that your BMR represents only your estimated resting calorie burn and does not include the energy you expend through daily activities, movement, or exercise. To estimate your total daily calorie needs, you would need to account for your activity level in addition to your BMR. Our TDEE Calculator can help you estimate your complete daily calorie expenditure by factoring in your activity level alongside your basal metabolic rate.
The BMR Formula
The Mifflin-St Jeor equation is the formula our calculator uses to estimate Basal Metabolic Rate. Introduced in 1990, research suggests this equation may provide more accurate BMR estimates for many individuals compared to older formulas like the Harris-Benedict equation. The formula uses your weight, height, age, and gender to calculate an estimate of the calories your body burns at rest for essential functions.
The Mifflin-St Jeor BMR Formulas
For Women:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
For Men:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
What the Equation Calculates
The Mifflin-St Jeor formula estimates your resting energy expenditure by accounting for your body mass, height, and age. The equation applies different calculations for men and women because biological differences in body composition can affect metabolic rate. Men typically have higher muscle mass relative to body weight, which may increase calorie burn at rest, while women generally have higher essential fat percentages necessary for reproductive health.
How the Formula Works
The formula multiplies your weight and height by specific factors that research suggests correlate with energy expenditure, then subtracts an age-related value to account for the natural metabolic slowdown that can occur over time. The final constant added to the equation (5 for men, -161 for women) represents the average metabolic difference between genders based on typical body composition patterns. Each component of the equation contributes to estimating how much energy your body may require to maintain vital functions like organ activity, cellular processes, and temperature regulation at rest.
Why Metric Units
The Mifflin-St Jeor equation was developed using metric measurements (kilograms and centimeters), which is why the multipliers in the formula are calibrated for these units. If you prefer to use imperial measurements (pounds and inches), our calculator automatically converts your inputs to metric before applying the formula, then provides your BMR result in calories per day. This ensures accurate calculations regardless of which measurement system you're more comfortable using.
How to Calculate Your BMR
Calculating your BMR manually involves using the Mifflin-St Jeor equation with your own personal measurements. While our calculator above handles this process instantly, understanding the calculation can help you see how your weight, height, age, and gender influence your estimated basal metabolic rate. The steps below show how to calculate BMR using the formula, including converting from imperial to metric units if needed.
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Step One
Calculate Your BMR
Formula for Women:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
Formula for Men:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
If using imperial units, convert to metric first:
Pounds ÷ 2.205 = kilograms
(Feet × 12 + inches) × 2.54 = centimeters
Example: 35-year-old man, 5'10", 180 lbs
Convert: 81.6 kg, 178 cm
BMR = (10 × 81.6) + (6.25 × 178) - (5 × 35) + 5 = 1,760 calories
Interpret Your Result
Your calculated BMR represents an estimate of the calories your body may burn at complete rest over 24 hours. This number reflects only your baseline metabolic needs for essential functions and does not include calories burned through daily activities, movement, or exercise. Remember that BMR calculations provide estimates based on population averages, and individual metabolic rates can vary based on factors like muscle mass, genetics, and overall health status.
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Instead of calculating manually, our free BMR calculator provides instant results in either metric or imperial units. Simply enter your information and receive your estimated BMR in seconds. If you want to know your total daily calorie needs including activity, our TDEE Calculator builds on your BMR by factoring in your activity level.
BMR vs TDEE
Understanding the Difference
BMR and TDEE are both measurements of calorie expenditure, but they represent different aspects of your body's energy needs. Understanding the distinction between these two metrics can help you make more informed decisions about your daily calorie intake and nutritional planning. While the terms are sometimes confused or used interchangeably, they measure fundamentally different things.
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Your Basal Metabolic Rate (BMR) represents only the calories your body may burn at complete rest to maintain essential life-sustaining functions like breathing, circulation, and cell production. This number does not include any physical activity, daily movement, or even the energy used to digest food. BMR is your body's baseline energy requirement—the minimum calories needed if you stayed in bed all day without moving.
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Total Daily Energy Expenditure (TDEE), on the other hand, represents an estimate of all the calories you may burn in a 24-hour period, including your BMR plus all additional activities. TDEE accounts for your basal metabolic rate, the calories burned through daily activities like walking and household tasks, the energy used during intentional exercise, and the thermic effect of food (calories burned during digestion). Research suggests that BMR typically accounts for approximately 60-75% of your TDEE, with the remaining calories coming from movement and digestion.
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The key practical difference is that BMR tells you your baseline calorie needs, while TDEE estimates your actual daily calorie requirements based on your lifestyle and activity level. Most people should base their nutrition plans on TDEE rather than BMR, since eating only enough calories to match your BMR may not provide adequate energy for daily activities and overall health. Our TDEE Calculator can help you estimate your total daily energy expenditure by applying an activity multiplier to your BMR, giving you a more complete picture of your calorie needs.
What Your BMR Tells You About Your Metabolism
Your BMR provides a window into how your unique metabolism functions and reveals important information about your body's baseline energy requirements. Knowing your basal metabolic rate can tell you about your metabolism and help you make informed decisions that support your health goals, rather than working against your body's natural needs. The insights from your BMR can guide more effective and sustainable approaches to nutrition and metabolic health.
Your Metabolism is More Active Than You Think
The good news about your BMR is that it represents the majority of your daily calorie burn—typically 60-75% of your total energy expenditure—without any effort on your part. Your body works around the clock to give you energy, burning hundreds or thousands of calories each day just through breathing, circulating blood, producing cells, and maintaining organ function. This means most of your calorie burn happens automatically, even while you sleep or rest.
You Can Positively Influence Your BMR
While factors like age and genetics play a role in your basal metabolic rate, research suggests you can take steps to support a healthy metabolism. Building and maintaining muscle mass through resistance training may help increase your BMR, since muscle tissue requires more energy at rest than fat tissue. Adequate protein intake, quality sleep, staying hydrated, and avoiding very low-calorie diets can all support healthy metabolic function over time.
Your Metabolism is Resilient and Adaptable
Your metabolism is designed to adapt to different conditions and support your health across various life stages and circumstances. While your BMR may fluctuate based on factors like stress, sleep, and activity patterns, your body has remarkable ability to adjust and maintain equilibrium. Understanding your BMR gives you knowledge about your body's needs, empowering you to make informed choices that support your metabolic health rather than working against it.
Your BMR serves as a foundation for understanding your metabolism, but it represents just one aspect of your overall metabolic health. Other factors like daily activity level, sleep quality, stress management, and muscle mass all contribute to your total metabolic picture. By knowing your BMR, you can work with your body's natural energy needs rather than against them, creating a more sustainable and health-supportive approach to nutrition and wellness.
How to Use Your BMR for Weight Loss
Understanding your BMR plays an important role in creating a healthy approach to weight loss, but it's essential to use this information correctly. Your basal metabolic rate represents the minimum calories your body needs at rest, which means it serves as a foundation for calculating appropriate calorie targets rather than being your actual target for weight loss. Using your BMR wisely can help you create sustainable calorie goals that support both your weight loss objectives and your overall health.
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The most important principle when using BMR for weight loss is that your daily calorie intake should not fall below your basal metabolic rate for extended periods. Eating significantly below your BMR may not provide adequate energy for essential functions like hormone production, immune system support, and vital organ function. Instead, your BMR helps you understand your baseline needs so you can create a calorie deficit from your Total Daily Energy Expenditure (TDEE), which accounts for your activity level in addition to your resting metabolism.
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To use your BMR effectively for weight loss, first calculate your TDEE by multiplying your BMR by an activity factor that reflects your daily movement and exercise patterns. Once you know your estimated TDEE, you can create a moderate calorie deficit—typically 250-500 calories below your TDEE—to support gradual weight loss while ensuring your intake stays well above your BMR. Our TDEE Calculator can help you determine your total daily calorie expenditure, and our Calorie Deficit Calculator can show you appropriate deficit ranges and timelines for reaching your weight loss goals.
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Your BMR can also help you understand why very low-calorie diets may feel unsustainable or why your energy levels might drop if your intake is too low. If you find yourself feeling persistently fatigued, irritable, or excessively hungry, your calorie intake may be too close to—or below—your BMR. Sustainable weight loss typically involves eating above your basal metabolic rate while creating a modest deficit from your TDEE, allowing your body to function optimally while gradually using stored energy.
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Remember that BMR calculators provide estimates, and individual responses to calorie reduction can vary based on factors like stress, sleep, activity patterns, and metabolic health. If you're planning significant changes to your calorie intake for weight loss, working with a registered dietitian or healthcare provider can help you create an approach that's appropriate for your individual circumstances and health status. They can help ensure your calorie targets support both your weight goals and your overall metabolic health.
How to Increase Your BMR
While certain factors that influence your BMR like age, height, and genetics are beyond your control, there are several evidence-based strategies that may help support or increase your basal metabolic rate over time. These approaches focus on building metabolically active tissue, supporting healthy metabolic function, and avoiding practices that can slow metabolism. Making sustainable changes in these areas can positively impact your resting calorie burn and metabolic health.
Build and Maintain Muscle Mass
Resistance training and strength-building exercises may be one of the most effective ways to increase your BMR, as muscle tissue requires more energy at rest compared to fat tissue. Research suggests that adding lean muscle mass through activities like weight lifting, resistance bands, or bodyweight exercises can help increase your resting metabolic rate. Combining regular resistance training with adequate protein intake provides your body with the building blocks needed to develop and maintain metabolically active muscle tissue.
Eat Enough Calories and Protein
Paradoxically, eating too few calories for extended periods can actually slow your metabolic rate as your body adapts to conserve energy. Ensuring your calorie intake stays above your BMR and includes adequate protein (research suggests 0.7-1.0 grams per pound of body weight) can help support healthy metabolic function. Protein also has a higher thermic effect than carbohydrates or fats, meaning your body burns more calories digesting and processing protein-rich foods.
Prioritize Sleep and Manage Stress
Quality sleep and stress management play important roles in metabolic health and may influence your BMR. Research indicates that chronic sleep deprivation can negatively affect metabolic rate and hormone production, while consistently getting 7-9 hours of quality sleep may help support healthy metabolic function. Managing chronic stress through activities like walking, meditation, or time in nature can also support hormonal balance and metabolic health.
Stay Active Throughout the Day
While BMR specifically measures resting metabolism, increasing your overall daily movement through non-exercise activity (walking, taking stairs, household tasks) can complement your BMR and support total daily calorie expenditure. More importantly, regular physical activity—both resistance training and cardiovascular exercise—can help preserve muscle mass as you age, which supports maintaining a healthy BMR over time. Our TDEE Calculator can show you how different activity levels affect your total daily calorie burn.
BMR Calculator for Men and Women
Our BMR calculator provides personalized estimates for both women and men, accounting for the physiological differences that affect basal metabolic rate between genders. Understanding why and how BMR differs between men and women can help you better interpret your results and set appropriate expectations for your individual calorie needs. These differences are rooted in body composition, hormonal profiles, and biological factors.
Men typically have higher BMRs than women of the same age, height, and weight, primarily due to differences in body composition. Research suggests that men generally have a higher percentage of lean muscle mass and lower body fat percentage compared to women, and since muscle tissue is more metabolically active than fat tissue, this contributes to higher resting calorie expenditure. The Mifflin-St Jeor equation accounts for this difference through gender-specific constants in the formula: adding 5 for men and subtracting 161 for women, which reflects the average metabolic difference based on typical body composition.
Women's body composition includes higher essential fat percentages necessary for reproductive health and hormone production, which is completely normal and healthy. While fat tissue is less metabolically active than muscle, women's bodies are designed to maintain these fat stores for important biological functions including menstruation, pregnancy, and overall hormonal balance.
Women may also experience natural BMR fluctuations related to hormonal cycles that men typically don't encounter. The menstrual cycle can cause slight variations in metabolic rate, with some research suggesting a modest increase in the luteal phase (the two weeks before menstruation). Pregnancy significantly increases BMR to support fetal development, while menopause can affect metabolic rate through hormonal changes and body composition shifts. These fluctuations are normal metabolic adaptations, and understanding them can help women interpret changes in energy levels or weight more accurately.
Both men and women can support healthy BMRs through similar strategies: building and maintaining muscle mass, eating adequate protein and calories, prioritizing quality sleep, and managing stress. While the absolute numbers may differ between genders, the principles of metabolic health apply equally to everyone. Individual variation within each gender is often greater than the average difference between genders, meaning your personal BMR depends more on your unique characteristics—age, height, weight, muscle mass, and genetics—than on gender alone. Our calculator provides estimates tailored to your specific information, helping you understand your individual baseline calorie needs regardless of gender.
Factors That Affect Your BMR Results
Your Basal Metabolic Rate is influenced by multiple biological, physiological, and lifestyle factors that work together to determine your individual resting calorie expenditure. While BMR calculators account for major factors like age, gender, height, and weight, understanding the full range of influences on your metabolic rate can provide deeper insight into your body's energy needs. Some of these factors are within your control to modify, while others are determined by genetics and natural biological processes.
Body Composition and Muscle Mass
Individuals with higher muscle mass have higher BMRs because muscle tissue requires more energy at rest compared to fat tissue. This is one factor you can influence—building and maintaining lean muscle through resistance training and adequate protein intake may help support a higher BMR.
Diet History and Metabolic Adaptation
Long periods of very low-calorie dieting can lead to metabolic adaptation, where your body may reduce its energy expenditure. This may initially make weight management more challenging, but eating adequate calories and building muscle can help support metabolic recovery over time.
Height and Total Body Weight
Taller individuals and those who weigh more typically have higher BMRs because they have more total body mass, larger organs, and more cells that all require energy to maintain at rest. This is why height and weight are primary inputs in BMR calculations.
Genetics and Family History
Research suggests that genetics can account for variation in metabolic rate, with some individuals naturally having faster or slower metabolisms based on inherited traits. Your genetic background may influence your BMR in ways that standard calculators cannot fully capture.
Hydration Levels and Water Intake
Adequate hydration supports optimal metabolic function, as even mild dehydration can temporarily affect how efficiently your body processes energy at rest. Drinking enough water throughout the day may help support your body's ability to burn calories efficiently.
Sleep Quality and Duration
Research indicates that chronic sleep deprivation can negatively affect metabolic rate and the hormones that regulate hunger and energy expenditure. Getting consistent, quality sleep of 7-9 hours per night may help support healthy metabolic function and optimal BMR.
These factors interact in complex ways that make each person's BMR unique, which is why two people of similar age and size may have different calorie needs. Understanding these influences can help you interpret your BMR results more accurately and make informed decisions about nutrition and lifestyle. While you cannot control all factors affecting your BMR, focusing on modifiable elements like muscle mass, adequate calorie intake, and overall health can help you support optimal metabolic function for your individual needs.
Related Health Calculators
Explore Additional Body Metrics With These Related Calculators
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TDEE Calculator
Calculate your Total Daily Energy Expenditure by applying an activity multiplier to your BMR. Essential for figuring your actual daily calorie needs including movement and exercise, not just your resting metabolism.
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Calorie Calculator
Calculate your daily calorie needs based on your weight goals and activity level. Helpful for determining how many calories to eat for weight loss, maintenance, or gain based on your total energy expenditure.
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Calorie Deficit Calc.
Determine the calorie deficit needed to reach your weight loss goals and see your estimated timeline. Useful for creating a sustainable weight loss plan that stays above your BMR and under your TDEE.
Frequently Asked Questions About BMR Calculators
Q: How accurate are BMR calculators?
A: BMR calculators provide estimates based on validated equations and population averages, but individual metabolic rates can vary by 10-20% from calculated values due to factors like genetics, muscle mass, and health conditions. Use BMR calculator results as a helpful starting point rather than an exact measurement.
Q: What is a good BMR?
A: There's no universal "good" BMR—your ideal basal metabolic rate depends on your individual characteristics like height, weight, age, and gender. A BMR that falls within the expected range for your demographics and supports your health and energy levels is appropriate for you.
Q: Is BMR the same as RMR?
A: BMR and RMR are very similar and are often used interchangeably—BMR measures calories under strict laboratory conditions while RMR measures resting calories under less restrictive conditions. RMR may be about 10% higher than BMR, and most online calculators (ours included) use RMR to maintain accuracy in less restrictive conditions.
Q: Should I eat my BMR calories to lose weight?
A: No, you should not eat at or below your BMR for weight loss—your BMR represents the minimum calories your body needs for essential functions at rest. Instead, calculate your TDEE (which includes activity) and create a moderate deficit from that number while keeping your intake above your BMR.
Q: Can you actually increase your BMR?
A: While you can't dramatically change your BMR overnight, you can support a healthier metabolic rate by building muscle mass, eating adequate calories and protein, prioritizing quality sleep, and staying consistently active. These changes may lead to modest BMR increases over time, though individual responses vary.
Q: Does BMR change when you lose weight?
A: Yes, your BMR typically decreases as you lose weight because you have less total body mass to maintain. This is a normal physiological response—recalculating your BMR as you lose significant weight (every 10-15 pounds) can help you adjust your calorie targets appropriately.
Q: What's the difference between BMR and metabolism?
A: BMR is a specific measurement of the calories you burn at rest, while metabolism refers to all the chemical processes in your body that convert food into energy. Your BMR is one component of your overall metabolism, representing your baseline metabolic rate.
Q: How often should I recalculate my BMR?
A: You should recalculate your BMR whenever you experience significant weight changes (10+ pounds), reach a new decade of age, or notice substantial changes in body composition from muscle gain or loss. For most people, recalculating every few months or after notable changes is sufficient.
Q: Is a higher BMR better for weight loss?
A: A higher BMR means you burn more calories at rest, which can create more flexibility in your calorie intake for weight loss, but it doesn't guarantee easier weight loss. What matters most is creating an appropriate calorie deficit from your TDEE while eating above your BMR and maintaining consistency over time.
Q: Do men and women have different BMR formulas?
A: Yes, the Mifflin-St Jeor equation uses different calculations for men and women because biological differences in body composition affect metabolic rate. Men's formula adds 5 calories while women's subtracts 161 calories, reflecting the average metabolic difference based on typical muscle mass and body fat percentages.
A Note from Health Calcz
Disclaimer* - This BMR calculator provides educational information based on standard basal metabolic rate estimation formulas. Results are estimates for informational purposes only and should not be used for medical diagnosis, treatment decisions, or as nutrition prescriptions. BMR calculators use population averages and may not reflect individual metabolic rates or actual resting energy expenditure. Factors including muscle mass, genetics, hormones, medical conditions, metabolic history, thyroid function, and body composition affect basal metabolic rate in ways calculators cannot fully assess. This tool and information are not medical or nutritional advice and don't replace consultation with qualified healthcare professionals. BMR estimates should be used as a general guideline only and not as the sole basis for determining calorie intake or making dietary changes. For personalized nutrition guidance, metabolic health assessment, or concerns about your BMR calculator results, consult your doctor or registered dietitian. If you have medical conditions affecting metabolism (including thyroid disorders), are taking medications, are pregnant or breastfeeding, or have questions about appropriate calorie intake based on your BMR, contact your healthcare provider before making changes to your diet.