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Basal Metabolic Rate CalculatorCalculate your basal metabolic rate (BMR) using the scientifically-validated Mifflin-St Jeor equation. Determine your resting energy expenditure and daily calorie requirements for optimal nutrition planning and metabolic health assessment.
Input Metrics
Age
Gender
Weight (kg)
Height (cm)
1. What is Basal Metabolic Rate (BMR)?Basal Metabolic Rate (BMR) represents the minimum energy expenditure required to sustain vital physiological processes during complete metabolic rest. This encompasses cellular respiration, cardiovascular circulation, neurological function, hepatic metabolism, renal filtration, protein synthesis, and thermoregulation - collectively accounting for 60-75% of total daily energy expenditure in sedentary individuals.Formula: Mifflin-St Jeor Equation - the most accurate predictive equation for contemporary populations, validated across diverse demographic groups with superior precision compared to Harris-Benedict and other legacy formulas.
2. BMR vs TDEE: Understanding the Difference
BMR (Basal Metabolic Rate)Energy expenditure during complete metabolic rest - post-absorptive state, thermoneutral environment, minimal muscular activity, representing core physiological maintenance costs.
TDEE (Total Daily Energy Expenditure)BMR plus thermic effect of food (TEF), non-exercise activity thermogenesis (NEAT), and exercise activity thermogenesis (EAT) - representing total 24-hour energy expenditure.
3. Factors That Affect Your BMR
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    Age-Related Decline: BMR decreases approximately 1-2% per decade after age 20 due to sarcopenia, reduced organ mass, and hormonal changes
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    Sexual Dimorphism: Males exhibit 10-15% higher BMR due to greater lean body mass, larger organ size, and hormonal differences
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    Body Surface Area: Larger body mass and surface area increase metabolic demands for cellular maintenance and thermoregulation
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    Lean Body Mass: Skeletal muscle tissue exhibits 3-fold higher metabolic activity compared to adipose tissue at rest
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    Genetic Polymorphisms: Individual genetic variations can influence BMR by ±200-300 calories through metabolic enzyme efficiency
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    Endocrine Function: Thyroid hormones (T3/T4), cortisol, insulin, and growth hormone significantly modulate metabolic rate
4. Activity Level Multipliers (BMR to TDEE)
Activity LevelMultiplierDescription
SedentaryBMR × 1.2Little to no exercise, desk job
Lightly ActiveBMR × 1.375Light exercise 1-3 days/week
Moderately ActiveBMR × 1.55Moderate exercise 3-5 days/week
Very ActiveBMR × 1.725Hard exercise 6-7 days/week
Extremely ActiveBMR × 1.9Very hard exercise, physical job
5. BMR by Age and Gender (Average Values)
Men (calories/day)
20-29 years1,800-2,000
30-39 years1,750-1,950
40-49 years1,700-1,900
50-59 years1,650-1,850
60+ years1,600-1,800
Women (calories/day)
20-29 years1,400-1,600
30-39 years1,350-1,550
40-49 years1,300-1,500
50-59 years1,250-1,450
60+ years1,200-1,400
6. How to Boost Your Metabolic Rate
Strength TrainingProgressive resistance training increases lean body mass - each kilogram of skeletal muscle elevates BMR by approximately 13-15 calories daily compared to 4-5 calories for adipose tissue.
High-Intensity TrainingHigh-intensity interval training induces EPOC (excess post-exercise oxygen consumption), elevating metabolic rate for 12-24 hours post-exercise through oxygen debt repayment.
Protein IntakeDietary-induced thermogenesis - protein metabolism requires 20-30% of ingested calories for digestion, absorption, and utilization versus 5-10% for carbohydrates and lipids.
Quality SleepAdequate sleep duration (7-9 hours) optimizes circadian rhythm regulation of metabolic hormones including leptin, ghrelin, cortisol, and growth hormone secretion patterns.
Stay HydratedOptimal hydration maintains cellular metabolic efficiency - dehydration reduces BMR by 2-3%, while cold water thermogenesis can temporarily elevate energy expenditure by 10-30%.
Avoid Crash DietsSevere caloric restriction triggers adaptive thermogenesis, reducing BMR by 10-40% through decreased thyroid function, sympathetic nervous system activity, and lean mass preservation mechanisms.
7. Using BMR for Goal Setting
+300-500
Weight GainCalories above TDEE for lean muscle gain (0.5-1 lb/week)
TDEE
MaintenanceEat at TDEE level to maintain current weight
-300-750
Weight LossCalories below TDEE for fat loss (0.5-1.5 lb/week)
⚠️ Important Safety NoteChronic intake below BMR induces metabolic adaptation, sarcopenia, hormonal dysregulation, and compromised physiological function. Maintain minimum intake of BMR + 200-300 calories to preserve metabolic health and lean body mass.
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TDEE CalculatorTotal daily energyMacro CalculatorMacronutrient ratiosBody Fat CalculatorBody compositionBMI CalculatorWeight status