Enter your details to compute Basal Metabolic Rate
Enter your details and click Calculate BMR to see your basal metabolic rate and daily calorie breakdown
Learn the biological factors that dictate your BMR and how metabolic equations compare.
Your Basal Metabolic Rate is the number of calories your body burns at complete rest to stay alive and fuel basic autonomic processes (breathing, cell division, temperature control).
We show Mifflin-St Jeor (standard), Harris-Benedict (revised, best for classic stats), and Katch-McArdle (highly accurate for fit individuals by factoring in lean tissue mass).
While BMR is your zero-activity baseline energy expenditure, TDEE (Total Daily Energy Expenditure) adds activity, exercise, and the digestive thermal effect on top of BMR.
Muscle mass increases BMR significantly, while aging naturally lowers it. Tall stature, genetics, body temperature, hormonal status (thyroid), and gender also modify it.
Your Basal Metabolic Rate (BMR) represents the physiological energy baseline of your existence. In layman's terms, BMR is the exact amount of daily energy, measured in calories (kilocalories), that your body must burn to maintain life-sustaining autonomic processes while you are completely asleep, motionless, and in a fasted state under a thermoneutral environment. Even if you were to lay in bed completely still for 24 hours without moving a single finger, your heart would still need to pump blood, your kidneys would filter toxins, your lungs would expand, and billions of cells would synthesize proteins. This BMR calculator uses three of the most historically validated and peer-reviewed mathematical equations in clinical nutrition: the Mifflin-St Jeor equation, the Revised Harris-Benedict equation, and the Katch-McArdle formula.
Many fitness enthusiasts confuse Basal Metabolic Rate (BMR) with Total Daily Energy Expenditure (TDEE). Understanding the distinction is vital for accurate diet planning. Think of your BMR as your car's engine idling in park; it burns gasoline just to stay on, but it isn't driving anywhere. Your TDEE is the total fuel consumed once the car is driving down the road. TDEE incorporates your BMR plus three other metabolic variables:
In short, BMR is the base; TDEE is the total. To calculate TDEE, BMR is multiplied by an activity level factor ranging from 1.2 to 1.9.
This BMR calculator estimates your basal metabolic rate using three different scientific models, each with distinct advantages:
Published in 1990 by MD Mifflin and ST St Jeor, this formula was developed to reflect modern body compositions better than older equations. It has become the gold standard in clinical settings and is recommended by the Academy of Nutrition and Dietetics. It utilizes gender, weight, height, and age to determine resting metabolic needs.
The original Harris-Benedict equation was created in 1918. However, in 1984, researchers Roza and Shizgal updated it using more modern subjects. While highly reliable, the Revised Harris-Benedict formula tends to overestimate BMR slightly, particularly in overweight individuals, but remains very popular in athletic coaching circles.
While the previous equations rely on total body weight, they do not distinguish between fat mass and muscle mass. The Katch-McArdle formula calculates BMR using **Lean Body Mass (LBM)** or Fat-Free Mass. Because muscle tissue is far more metabolically active than fat tissue at rest, this formula is extremely accurate for individuals with low body fat or high muscularity, such as athletes, bodybuilders, and fitness professionals.
No two human bodies are identical, and BMR fluctuates based on multiple physiological and environmental variables:
Your BMR is the foundation of weight management. To lose weight safely, you should calculate your TDEE (BMR multiplied by activity factor) and set a caloric target below it, but **never eat below your BMR without medical supervision**. Restricting intake below BMR deprives organs of energy, resulting in muscle loss, fatigue, hormone dysregulation, and a damaged metabolism. By combining BMR calculations with a modest caloric deficit (eating at 200–500 kcal below TDEE) and resistance training, you can achieve healthy fat loss while preserving metabolic health and precious muscle tissue. For a comprehensive assessment of your healthy weight, you can cross-reference your BMR with our BMI Calculator, plan specific macro distributions with the Macro Calculator, or determine exact daily target calories using the Calorie Calculator.
BMR is the baseline amount of energy (calories) your body burns to maintain basic, life-sustaining bodily functions like breathing, blood circulation, cellular regeneration, and organ operations when at absolute physical and mental rest.
BMR is your resting metabolic baseline. TDEE (Total Daily Energy Expenditure) is your BMR plus all calories burned through physical activity, standard movements throughout the day, and digestion. TDEE represents your true daily maintenance calories.
For the average person, Mifflin-St Jeor is the most accurate and widely used formula in clinical environments. However, for lean, muscular athletes, the Katch-McArdle formula is superior because it uses Lean Body Mass to calculate metabolic rate.
No, you should avoid eating below your BMR. Eating fewer calories than your BMR forces your body to break down muscle tissue for energy and slows down your metabolism (metabolic adaptation), which makes long-term weight management more difficult and can lead to nutrient deficiencies and chronic fatigue.
The best long-term method to increase your BMR is to build lean muscle mass through resistance training. Muscle tissue is metabolically active and burns more calories at rest than body fat. Eating enough protein and maintaining physical activity also keeps your metabolism running efficiently.
Yes. BMR naturally declines as you get older, typically by 1% to 2% per decade after early adulthood. This is largely because people tend to lose muscle mass and become less active as they age. Strength training can help combat this age-related metabolic decline.
