BMR Calculator

Determine your Basal Metabolic Rate (BMR)—the baseline calories your body requires to function at complete rest. Compare standard medical equations, project daily activity maintenance requirements (TDEE), and calculate targeted macro distributions.

Your Physical Profile
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Include Body Fat (Katch-McArdle)
Mifflin-St Jeor Equation Moderate Metabolic Rate
0 kcal / day
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Daily Maintenance Requirements (TDEE)

Your estimated Total Daily Energy Expenditure (TDEE) based on activity multipliers:

Sedentary Desk job, little to no structured exercise
0 kcal 1.2x factor
Lightly Active Light workouts, sports, or active hobbies 1-3 days/week
0 kcal 1.375x factor
Moderately Active Moderate training or sports 3-5 days/week
0 kcal 1.55x factor
Very Active Hard training or intense sports 6-7 days/week
0 kcal 1.725x factor
Extra Active Athletic training twice daily, heavy labor job
0 kcal 1.9x factor
Methodology Comparisons

Compare calculated BMR scores across popular medical formulas:

Mifflin-St Jeor
0 kcal

Clinical standard. Reliable estimate based on standard anthropometry.

Harris-Benedict
0 kcal

Traditional equation. Tends to slightly overestimate requirements.

Katch-McArdle
0 kcal

Lean mass equation. Requires active body fat percentage inputs.

Daily Goal Target & Macronutrients
Maintenance Goal

Calorie balance matches expenditure.

0 kcal/day
Protein (30% split) 0g (0 kcal)
Carbohydrates (40% split) 0g (0 kcal)
Fats (30% split) 0g (0 kcal)

Understanding Basal Metabolic Rate (BMR)

Basal Metabolic Rate, or BMR, represents the absolute minimum amount of energy (measured in calories) your body needs to maintain vital life-sustaining processes at complete physical and digestive rest in a temperate environment. These vital processes include respiratory functions, blood circulation, cell division, hormone production, protein synthesis, and body temperature regulation. Essentially, if you spent 24 hours lying completely motionless in bed, your body would still burn this quantity of energy just to stay alive.

Key Metabolic Formulas Compared

Sports scientists and medical organizations utilize standard algebraic regression equations to estimate BMR:

  • Mifflin-St Jeor Equation: Developed in 1990, this formula is currently the clinical standard recommended by the Academy of Nutrition and Dietetics. It has been shown to predict resting energy expenditure to within 10% of measured calorimetry for most adults.
  • Harris-Benedict Equation (Revised): Originally formulated in 1918 and updated in 1984 by Roza and Shizgal, this remains a popular traditional baseline. It relies on total body weight and may occasionally overestimate BMR in highly muscular or overweight individuals.
  • Katch-McArdle Formula: If you input your body fat percentage, the tool activates this lean-mass-based method. Because fat-free muscle tissue is much more metabolically active than adipose fat tissue, the Katch-McArdle equation is widely regarded as the most accurate model for active athletes and body recomposition planning.

Mapping BMR to Total Energy Output (TDEE)

While BMR represents resting energy, your actual daily energy expenditure is higher due to physical movement. To estimate your Total Daily Energy Expenditure (TDEE), we apply standard activity factor multipliers (often called the Katch-McArdle or Harris-Benedict activity multipliers) to your baseline BMR score:

  • Sedentary (1.2x): Desk job, minimal walking, and no scheduled workouts.
  • Lightly Active (1.375x): Active hobbies or light workouts 1 to 3 days per week.
  • Moderately Active (1.55x): Structured exercise or active sports 3 to 5 days per week.
  • Very Active (1.725x): Heavy cardiovascular or resistance workouts 6 to 7 days per week.
  • Extra Active (1.9x): Strenuous labor occupations or dual athletic training sessions.

Adjusting Calories for Weight Goals & Macronutrients

Using your Moderately Active TDEE as a reference baseline, the Goal Planner maps calories to targeted physiological plans. Achieving fat loss requires a caloric deficit, typically achieved through a standard reduction of 500 kcal/day to support a safe, sustainable fat loss rate. Conversely, building lean muscle mass requires a mild caloric surplus (approximately 300 kcal/day) paired with heavy progressive resistance training. To support metabolic health, hormonal balance, and muscle retention, our goal models calculate a balanced macronutrient distribution consisting of 30% Protein, 40% Carbohydrates, and 30% healthy Fats.