BMR Calculator
Calculate your Basal Metabolic Rate and daily calorie needs with precision
What is a BMR Calculator?
A BMR (Basal Metabolic Rate) calculator is a scientific tool that determines the minimum number of calories your body needs to maintain basic physiological functions while at complete rest. This includes essential processes like breathing, circulation, cell production, nutrient processing, and protein synthesis. Understanding your BMR is crucial for effective weight management, fitness planning, and maintaining optimal health.
Our advanced BMR calculator uses the most accurate scientific formulas including the Mifflin-St Jeor equation (recommended by nutritionists), Harris-Benedict equation, and Katch-McArdle formula for those who know their body fat percentage. The calculator considers your age, gender, height, and weight to provide personalized results that form the foundation for determining your Total Daily Energy Expenditure (TDEE) and creating effective nutrition plans.
This tool is essential for fitness enthusiasts planning workout nutrition, individuals trying to lose or gain weight, athletes optimizing performance nutrition, healthcare professionals assessing patient needs, and anyone interested in understanding their metabolic health. The results help you set realistic calorie targets, plan meal portions, and make informed decisions about diet and exercise routines.
Your Stats
Age, gender, height, weight
Calculate BMR
Metabolic rate analysis
Nutrition Plan
Personalized calorie goals
Personal Information
Weight Management Goals
Recommended Macronutrient Breakdown
BMR Formulas & Scientific References
BMR Calculation Formulas
Where m = mass (kg), h = height (cm), a = age (years). Most accurate equation for modern populations, developed in 1990. Accuracy: ±10% for 68% of population.
Where m = mass (kg), h = height (cm), a = age (years). Classic equation revised in 1984. Slightly less accurate than Mifflin-St Jeor for modern lifestyles.
Where LBM = lean body mass (kg), m = total mass (kg), BF = body fat percentage (decimal). Most accurate when body fat percentage is known. Used by fitness professionals.
Activity Level Multipliers
Where AF = activity factor. Multiplies BMR by activity level to estimate total daily calorie needs.
Based on comprehensive metabolic studies and activity tracking research.
Scientific References
Original study establishing the Mifflin-St Jeor equation with 498 healthy subjects.
American Journal of Clinical NutritionClassic metabolic research updated with modern population data by Roza & Shizgal.
American Journal of Clinical NutritionValidation study comparing BMR prediction equations in athletic populations.
Journal of Sports MedicineInternational standards for human energy requirements and metabolic calculations.
FAO Food and NutritionMetabolic Science
Energy expenditure at rest in thermoneutral environment, 12+ hours fasted, measured via indirect calorimetry.
Similar to BMR but measured under less restrictive conditions. Typically 10-15% higher than BMR.
Energy cost of digesting, absorbing, and processing food. Approximately 8-10% of total daily expenditure.
Energy expended for activities that are not sleeping, eating, or sports-like exercise.
Accuracy & Limitations
Mifflin-St Jeor: ±10% for 68% of population, ±20% for 95% of population.
Genetics, muscle mass, hormones, and metabolic health can cause 15-20% variation from predicted values.
Metabolic rate decreases ~2-3% per decade after age 30 due to muscle mass loss and hormonal changes.
Muscle tissue burns 3x more calories than fat tissue. Athletes may need body fat-based calculations.
Thyroid disorders, diabetes, and medications can significantly affect metabolic rate. Consult healthcare providers.