BMR Calculator

BMR Calculator

What is BMR? 

Basal Metabolic Rate (BMR) is the amount of energy expended by the body while at rest in a neutrally temperate environment, in a post-absorptive state (meaning the digestive system is inactive, typically achieved after fasting for about 12 hours). It represents the minimum number of calories needed to sustain vital physiological functions such as heartbeat, breathing, and maintaining body temperature. Imagine it as the fuel your body needs to keep the engine running even when the car is parked. This energy primarily sustains vital organs such as the heart, brain, kidneys, and lungs, ensuring their continuous operation 

BMR is measured in calories per day and varies based on factors such as age, gender, height, weight, muscle mass, genetics, and overall metabolic health. 

How does the BMR Calculator Work? 

The BMR Calculator serves as a powerful tool, providing insights into your body’s energy requirements and laying the groundwork for achieving your health and fitness goals.  


Here are the steps for using the BMR calculator: 

Step 1: Enter your gender. 

Step 2: Input your age. 

Step 3: Enter your height and weight, specifying whether you prefer to use feet/inches or meters/kilograms. 

Step 4: Click on the “Calculate” button to generate your Basal Metabolic Rate (BMR) result. 

What Factors Influence BMR?

Several factors influence your BMR, reflecting the intricate interplay between physiological, environmental, and genetic determinants. Muscle mass plays a pivotal role in dictating BMR, with higher muscle mass correlating to increased energy expenditure at rest. As a result, individuals with greater muscle mass typically exhibit higher BMR values, necessitating a higher caloric intake to meet their energy needs. Age also exerts a significant influence on BMR, with older individuals often experiencing a decline in metabolic rate due to age-related changes in muscle mass and metabolism. Additionally, genetics and environmental factors such as weather, diet, and lifestyle habits contribute to variations in BMR among individuals, highlighting the multifaceted nature of metabolic regulation. 


How to Calculate  BMR with Equations and Formulas 

The BMR Calculator employs various equations and formulas to estimate your basal metabolic rate accurately. Among these, the Mifflin-St Jeor Equation stands out for its precision and widespread adoption in clinical practice. This equation takes into account essential variables such as gender, age, height, and weight, providing a comprehensive framework for estimating BMR. 


Mifflin-St Jeor Equation: 

For men: 

BMR = 10W + 6.25H – 5A + 5 


For women: 

BMR = 10W + 6.25H – 5A – 161 


Revised Harris-Benedict Equation: 

For men: 

BMR = 13.397W + 4.799H – 5.677A + 88.362 


For women: 

BMR = 9.247W + 3.098H – 4.330A + 447.593 


Katch-McArdle Formula: 

BMR = 370 + 21.6(1 – F)W 


W is body weight in kg 

H is body height in cm 

A is age 

F is body fat in percentage 


Practical Applications: Tailoring Your Health Journey 

Understanding your BMR serves as a cornerstone for optimizing your health and fitness journey, empowering you to make informed decisions regarding nutrition, exercise, and overall lifestyle choices. By knowing your body’s energy requirements, you can develop personalized nutrition plans tailored to your specific goals, whether it’s weight maintenance, fat loss, or muscle gain. Additionally, leveraging your BMR enables you to set realistic fitness goals based on your metabolic profile, ensuring sustainable progress and long-term success. Whether you’re embarking on a weight loss journey or striving to improve athletic performance, incorporating BMR calculations into your health regimen provides a solid foundation for achieving optimal outcomes. 


Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR, Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine1. Am J Clin Nutr 2005; 82: 941-948.

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