BMR Calculator
Calculate your basal metabolic rate.
Understanding BMR Calculator
Basal Metabolic Rate (BMR) is an estimate of the amount of energy the body requires to maintain essential physiological functions while at complete rest. Even without exercise or physical activity, the body continuously uses energy to support breathing, circulation, body temperature regulation, nervous system activity, cellular processes, and the normal function of organs and tissues.
BMR is one of the major components of total daily energy expenditure. It should not be confused with the total number of calories a person needs each day because normal daily energy use also includes walking, exercise, work, digestion, and other physical activities.
A practical way to use this calculator
BMR Calculator is most useful when the measurements you enter are taken using the same units and definitions shown beside each field. The calculator asks for values such as Age, Gender, Height (cm), Weight (kg); enter the measurements as accurately and consistently as possible rather than rounding them before calculation.
A useful detail to keep in mind
The number produced by this tool should be read in the context of the inputs and the method used by the calculator. A calculated health or fitness figure can be useful for education, planning, or tracking change over time, but it does not by itself describe every aspect of an individual’s health.
About BMR Calculator
Basal Metabolic Rate (BMR) is an estimate of the amount of energy the body requires to maintain essential physiological functions while at complete rest. Even without exercise or physical activity, the body continuously uses energy to support breathing, circulation, body temperature regulation, nervous system activity, cellular processes, and the normal function of organs and tissues.
BMR is one of the major components of total daily energy expenditure. It should not be confused with the total number of calories a person needs each day because normal daily energy use also includes walking, exercise, work, digestion, and other physical activities.
This calculator uses the Mifflin-St Jeor equation to estimate BMR from age, sex, height, and body weight. Because it is a predictive equation, the calculated value is an estimate rather than a direct measurement of an individual's metabolism.
How BMR Is Calculated
The Mifflin-St Jeor equation estimates resting energy requirements using body weight, height, age, and sex. Weight is measured in kilograms and height in centimeters.
BMR = 10W + 6.25H − 5A + 5
Women:
BMR = 10W + 6.25H − 5A − 161
In the equation, W represents weight in kilograms, H represents height in centimeters, and A represents age in years.
What Does BMR Include?
Resting energy expenditure supports many processes that continue whether a person is awake and moving or lying still. The heart requires energy to pump blood, the lungs require energy for respiration, and the brain, liver, kidneys, and other organs continuously perform metabolic work.
The body also uses energy to maintain temperature, transport substances across cell membranes, support tissue maintenance, synthesize proteins, and perform countless biochemical reactions required for normal function.
BMR and Resting Metabolic Rate
BMR and Resting Metabolic Rate (RMR) are closely related concepts but are not technically identical. BMR is intended to represent energy expenditure under highly controlled resting conditions, while RMR is generally measured under somewhat less restrictive conditions.
Online calculators cannot directly measure metabolic rate. They use predictive equations developed from population data to provide an approximate estimate.
Factors That Affect BMR
Body size and body composition are important determinants of resting energy expenditure. Lean tissues and metabolically active organs contribute significantly to the energy required at rest.
Age also affects energy expenditure. Changes in body composition and the amount of metabolically active tissue can contribute to differences in resting energy requirements as people age.
Genetics, hormonal status, illness, medications, environmental temperature, body composition, and prolonged changes in energy intake can also influence actual metabolic rate. These factors are not individually measured by this calculator.
BMR vs. Total Daily Energy Expenditure
BMR represents only resting energy requirements. Total Daily Energy Expenditure (TDEE) includes additional energy used through daily movement, exercise, digestion, and other activities.
For this reason, a person's daily calorie requirement will normally be higher than their calculated BMR.
Estimated Energy Requirements by Activity
Light Activity: BMR × 1.375
Moderate Activity: BMR × 1.55
Heavy Activity: BMR × 1.725
Very High Activity: BMR × 1.90
These activity multipliers are commonly used approximations. Actual energy expenditure may be higher or lower depending on exercise intensity, occupation, daily movement, body composition, and individual metabolism.
BMR and Weight Management
BMR can be used as a starting point when estimating calorie requirements for weight management. However, weight change is determined by overall energy balance over time rather than BMR alone.
When body weight changes, estimated energy requirements can also change. Physical activity and changes in body composition may further influence total energy expenditure.
Why Calculated BMR May Differ From Actual Metabolism
Predictive equations estimate average relationships observed in populations. Two people with the same age, height, weight, and sex may still have different actual resting energy expenditures.
Differences in muscle mass, organ size, genetics, hormones, body composition, health status, and other physiological characteristics can contribute to this variation.
Understanding the Results
The calculator displays your estimated BMR together with approximate calorie requirements at several activity levels. The activity-based estimates are calculated by multiplying BMR by a standard activity factor.
These values are useful for general calorie planning, but they should be treated as estimates rather than exact measurements of your metabolism or personalized nutritional prescriptions.
Example
Gender: Male
Height: 175 cm
Weight: 70 kg
BMR = 10(70) + 6.25(175) − 5(30) + 5
BMR = 700 + 1,093.75 − 150 + 5
BMR ≈ 1,649 kcal/day
Moderate Activity Estimate:
1,649 × 1.55 ≈ 2,556 kcal/day
Important Considerations
BMR calculators are designed for general educational and estimation purposes. They cannot diagnose metabolic disorders or determine an individual's exact calorie requirements.
Energy requirements can differ substantially during pregnancy, breastfeeding, childhood, adolescence, intensive athletic training, significant changes in body composition, or certain medical conditions. Individualized assessment may be appropriate in these circumstances.
Medical Disclaimer
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for medical decisions.