BMR & TDEE Calculator - Basal Metabolic Rate Calculator
⚕️ Free professional tool: Calculate your BMR & TDEE instantly with Mifflin-St Jeor accuracy. Get personalized calorie needs for weight loss, maintenance, muscle gain, and fat loss. 150,000+ users trust our accurate metabolism calculator.
The Basal Metabolic Rate (BMR) and calorie calculator estimates the minimum daily energy required at rest using the Mifflin-St Jeor or Harris-Benedict equation. Inputs include body weight, height, age, and sex. Results inform daily calorie targets for weight management aligned with USDA Dietary Guidelines.
Formula & Methodology
BMR (men) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + 5. BMR (women) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) − 161. TDEE = BMR × Activity Factor.
Variables: Weight in kilograms. Height in centimetres. Age in years. Activity factor ranges from 1.2 (sedentary) to 1.9 (very active).
Worked Example: A 35-year-old woman weighing 65 kg and 165 cm tall: BMR = (10 × 65) + (6.25 × 165) − (5 × 35) − 161 = 1395 kcal/day then multiplied by 1.55 for moderate activity = 2162 kcal/day TDEE.
Calculations use the Mifflin-St Jeor equation (1990), validated by the Academy of Nutrition and Dietetics as the most accurate predictive BMR formula for most adults. Activity multipliers follow USDA Dietary Guidelines 2020-2025 Physical Activity Equivalents.
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How BMR & TDEE Calculation Works - Medical Methodology
Our BMR Calculation System uses Mifflin-St Jeor medical formulas to provide accurate metabolic assessments and calorie planning insights. Here's the complete technical methodology:
Mifflin-St Jeor BMR Formula: For men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) - 161. This is the gold standard for metabolic calculation.
TDEE Calculation: Total Daily Energy Expenditure = BMR × Activity Multiplier. Multipliers: Sedentary (1.2), Lightly Active (1.375), Moderately Active (1.55), Very Active (1.725), Super Active (1.9). This accounts for all daily energy expenditure.
Weight Management Calorie Targets: Weight Loss: TDEE - 500 calories (lose ~0.5kg/week). Weight Maintenance: TDEE ± 0 calories. Muscle Gain: TDEE + 500 calories (gain ~0.5kg/week). These are safe, sustainable targets.
Body Fat Adjusted BMR: Optional body fat percentage input adjusts BMR using the Katch-McArdle formula: BMR = 370 + (21.6 × Lean Body Mass in kg). Lean Body Mass = Weight × (1 - Body Fat Percentage).
AI Accuracy Enhancement: Our algorithms incorporate metabolic research data across different populations, ages, and fitness levels to provide context-aware nutrition recommendations and fitness planning.
Metabolism & Nutrition Strategies
- Track consistently - regular BMR monitoring helps identify metabolic trends and adjust nutrition plans accordingly
- Consider body composition - BMR is influenced by muscle mass; strength training increases metabolic rate over time
- Adjust for activity changes - recalculate TDEE whenever your exercise routine or daily activity levels change
- Focus on nutrient timing - distribute protein intake throughout the day to support muscle maintenance and metabolic health
- Consult nutrition professionals - for personalized dietary guidance and medical conditions, seek professional advice
- Stay hydrated - water consumption can temporarily increase metabolic rate by up to 30% for about an hour
- Prioritize sleep - quality sleep regulates hormones that control appetite and metabolism
BMR & TDEE Frequently Asked Questions
It calculates your Basal Metabolic Rate — the calories your body burns at rest — and your Total Daily Energy Expenditure based on activity level using the Mifflin-St Jeor equation.
It uses the Mifflin-St Jeor equation (1990), which the Academy of Nutrition and Dietetics considers the most accurate BMR formula for most adults.
For a moderately active 30-year-old woman at 60 kg and 163 cm, BMR is approximately 1380 kcal/day and TDEE around 2139 kcal/day.
BMR is the energy used at complete rest. TDEE multiplies BMR by an activity factor to estimate actual daily calorie expenditure including movement and exercise.
Overestimating your activity level. Choose "sedentary" or "lightly active" unless you genuinely exercise intensely most days — this prevents underestimating calorie needs.
A deficit of approximately 500 kcal per day below your TDEE leads to roughly 0.5 kg of fat loss per week, as 1 kg of body fat contains about 7700 kcal.