BMR Calculator - Calculate Your Basal Metabolic Rate

Understanding Basal Metabolic Rate (BMR)

Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR) are measures of resting energy expenditure, representing the minimum amount of energy required to sustain the body's vital functions, including the heart, lungs and temperature regulation.

The BMR can account for about 60-70% of the body's daily energy consumption. BMR goes to supporting the ongoing metabolic work of the body's cells, such activities as pumping blood around the body, digesting food, respiration, maintaining body temperature and for cells to grow.

By multiplying BMR by an activity factor, you can estimate how many calories are required each day to maintain body weight based on your daily activity level.

Harris-Benedict Equation for Calculating BMR

The Harris-Benedict Equation (Harris & Benedict, 1919) has for a long time been the standard formula and is widely used for estimating BMR. The Harris-Benedict equation was first published in 1919. Since then there have been many other studies attempting to improve it, with limited success.

Metric Units

• Men: BMR = 66.47 + ( 13.76 × weight in kg ) + ( 5.003 × height in cm ) – ( 6.755 × age in years )
• Women: BMR = 655.1 + ( 9.563 × weight in kg ) + ( 1.850 × height in cm ) – ( 4.676 × age in years )

Imperial Units

• Men: BMR = 66.47 + ( 6.24 × weight in pounds ) + ( 12.7 × height in inches ) – ( 6.755 × age in years )
• Women: BMR = 655.1 + ( 4.35 × weight in pounds ) + ( 4.7 × height in inches ) - ( 4.676 × age in years )

Mifflin-St Jeor Equation for Calculating BMR

For men: BMR (kcal / day) = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5

For women: BMR (kcal / day) = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Mifflin Equation for Calculating BMR

Another commonly used equation for calculating RMR is the Mifflin equation. Use the calculations below to calculate BMR, where: Wt = weight in kg, Ht = height in cm, A = age in years.

men: kcal/day = (13.75 x Wt) + (5 x Ht) - (6.76 x Age) + 66
women: kcal/day = (9.56 x Wt) + (1.85 x Ht) - (4.68 x Age) + 655

Schofield Equation for Calculating BMR

Use the table below to find the equation for estimating BMR for the appropriate age and sex category, using weight in kilograms (Warwick, 1989).

Men

Women

How to Use the BMR Calculator

Our BMR calculator provides athletes and fitness enthusiasts with accurate metabolic rate calculations using four scientifically validated formulas. Follow these steps for best results:

1. Enter Your Body Measurements: Input your weight (kg or lbs) and height (cm or inches). Athletes should use their current competition weight for most accurate results.
2. Provide Age and Sex: These factors significantly impact BMR. Biological sex affects muscle mass distribution and hormonal influences on metabolism.
3. Select a Formula: The Mifflin-St Jeor equation is recommended for general population, while athletes may prefer Harris-Benedict for its widespread use in sports nutrition.
4. Review Your Results: Your BMR represents calories burned at complete rest. The activity multipliers show your Total Daily Energy Expenditure (TDEE) based on training intensity.

For athletes, knowing your BMR is crucial for periodization nutrition, weight cutting strategies, and optimizing body composition during different training phases.

BMR for Different Athletes and Sports

Basal Metabolic Rate varies significantly across different sports and athlete types due to differences in body composition, training demands, and physiological adaptations:

Endurance Athletes

Marathon runners, cyclists, and triathletes typically have lower BMRs relative to body weight due to lower muscle mass and metabolic efficiency adaptations. However, their high training volumes result in substantial total energy expenditure. Elite endurance athletes may burn 3,000-5,000 calories daily during heavy training periods.

Power and Strength Athletes

Powerlifters, Olympic weightlifters, and bodybuilders generally have higher BMRs due to increased muscle mass. Muscle tissue is metabolically active, burning approximately 6 calories per pound daily at rest, compared to 2 calories for fat tissue. A 200-pound bodybuilder may have a BMR exceeding 2,200 calories.

Team Sport Athletes

Football, basketball, and soccer players require balanced metabolic profiles. Their BMRs typically fall between endurance and power athletes, with energy needs varying by position. A linebacker's BMR might be 2,000+ calories, while a midfielder's could be 1,600-1,800 calories.

Combat Sport Athletes

MMA fighters, boxers, and wrestlers face unique challenges with weight cutting. Understanding BMR helps manage safe weight reduction while maintaining performance. These athletes often cycle between higher off-season BMRs and reduced pre-competition levels.

Factors Affecting Athletic BMR

Several factors influence an athlete's basal metabolic rate beyond the basic calculations:

• Muscle Mass: Each pound of muscle burns approximately 6-10 calories daily at rest. Athletes with higher lean body mass percentages have elevated BMRs.
• Training Adaptation: Regular intense training can increase BMR by 5-10% through mitochondrial adaptations and increased protein turnover.
• Recovery State: Post-exercise oxygen consumption (EPOC) can elevate metabolism for 24-48 hours after intense training.
• Hormonal Status: Testosterone, growth hormone, and thyroid hormones significantly impact metabolic rate. Overtraining can suppress these hormones, lowering BMR.
• Genetics: Individual variations can create 200-300 calorie differences in BMR between similar individuals.
• Environmental Factors: Training at altitude, cold exposure, and heat acclimatization all influence metabolic rate.

Using BMR for Performance Nutrition

Athletes can optimize their nutrition strategies using BMR calculations:

Periodization Nutrition

Adjust caloric intake based on training phases. During base building, maintain calories at TDEE. In competition prep, create small deficits (200-300 calories) for body composition improvements without sacrificing performance.

Recovery Optimization

Ensure adequate calories for recovery by never dropping below BMR × 1.2, even on rest days. This supports protein synthesis, glycogen replenishment, and hormonal balance.

Weight Management

For healthy weight loss, athletes should maintain a deficit of 300-500 calories below TDEE, never dropping below BMR. For muscle gain, add 300-500 calories above TDEE with emphasis on protein timing.

Competition Preparation

Use BMR to plan safe weight cuts. Gradual reductions (1-2 pounds weekly) preserve muscle mass and performance. Rapid weight loss below BMR levels risks muscle loss and decreased power output.