About the Calorie Calculator
Whether your goal is fat loss, athletic performance, or muscle hypertrophy, managing your daily energy balance is the fundamental law of thermodynamics in human nutrition. This Calorie Calculator uses the peer-reviewed Mifflin-St Jeor equation—considered by the Academy of Nutrition and Dietetics to be the most accurate standard estimation formula—to compute your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).
How to Use This Calculator
- 1Select your age and biological sex.
- 2Enter your standing height (cm) and current body weight (kg).
- 3Choose the physical activity level that best matches your typical weekly routine.
- 4Review your maintenance calories alongside specific daily calorie targets for steady weight loss or muscle gain.
Formula & Calculation Methodology
BMR is calculated with the Mifflin-St Jeor equation: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + s, where s is +5 for males and -161 for females. TDEE is BMR multiplied by your physical activity factor.
Worked Example: Calorie Needs for a 30-Year-Old Active Male (75 kg, 175 cm)
Scenario: A 30-year-old male weighing 75 kg and standing 175 cm tall works out moderately 4 days per week (activity factor 1.55) and wants to lose 1 pound of fat per week.
Calculate Basal Metabolic Rate (BMR): (10 × 75) + (6.25 × 175) - (5 × 30) + 5
750 + 1,093.75 - 150 + 5 = 1,698.75 kcal
Multiply by activity factor (1.55): 1,698.75 × 1.55
2,633 kcal/day (Maintenance TDEE)
Apply standard 500 kcal deficit for fat loss: 2,633 - 500
2,133 kcal/day target
Conclusion: To maintain weight, consume ~2,633 calories per day. To achieve ~1 pound (~0.45 kg) of fat loss per week, consume ~2,133 calories daily.
Assumptions & Practical Limitations
- Formulas estimate metabolic rate based on total body weight rather than lean muscle mass. Highly muscular individuals will burn slightly more at rest.
- Metabolic adaptation occurs over extended dieting periods, meaning actual TDEE may gradually decrease as body weight drops.
Frequently Asked Questions
A deficit of 300 to 500 calories per day is widely recommended by dietitians for safe, sustainable fat loss (approximately 0.5 to 1.0 lb per week) while preserving lean muscle mass and energy levels.