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Calculate your Body Mass Index (BMI) and Basal Metabolic Rate (BMR). Find your Total Daily Energy Expenditure (TDEE) to manage weight scientifically.
Step-by-step breakdown of the underlying equations.
To lose 1lb per week, you should consume 1639 calories per day. To gain weight, aim for 2439 calories.
This calculator combines three essential health metrics: BMI (Body Mass Index), BMR (Basal Metabolic Rate), and TDEE (Total Daily Energy Expenditure). Together, they provide a science-based foundation for weight management.
The calculator uses the Mifflin-St Jeor equation, considered the most accurate BMR formula for most adults, and adjusts for your activity level to estimate your daily calorie needs.
Scenario: A 30-year-old male, 5'10" (178 cm), 180 lbs (82 kg), moderately active.
Important: These are estimates. Individual metabolism varies. Track your actual weight changes and adjust calorie intake accordingly.
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest—just to keep organs functioning, blood circulating, and cells regenerating. It accounts for 60-75% of daily calorie expenditure. Knowing your BMR helps set a realistic calorie target for weight goals.
BMI is a simple screening tool, not a diagnostic measure. It doesn't distinguish between muscle and fat—a muscular athlete may have a 'overweight' BMI while being very healthy. It's most useful for population-level health statistics. For individuals, combine BMI with body fat percentage and waist circumference for better assessment.
TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. It represents the total calories you burn per day including movement and exercise. Sedentary: BMR × 1.2, Lightly Active: BMR × 1.375, Moderately Active: BMR × 1.55, Very Active: BMR × 1.725.
A 500-calorie daily deficit typically leads to about 1 pound of weight loss per week (3,500 calories ≈ 1 lb of fat). Most experts recommend not going below 1,200 calories (women) or 1,500 calories (men) to ensure adequate nutrition. Slower weight loss (0.5-1 lb/week) is more sustainable long-term.
Metabolism decreases roughly 2-3% per decade after age 20, primarily due to loss of muscle mass (sarcopenia). Muscle tissue burns more calories than fat tissue. This is why strength training becomes increasingly important with age—maintaining muscle helps preserve metabolic rate.