Calorie Calculator (TDEE)

What Is BMR?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns while completely at rest — just to keep your heart beating, lungs breathing, and organs functioning. It represents the minimum energy needed to sustain life.

BMR accounts for roughly 60–75% of your total caloric expenditure. It is influenced by your age, sex, height, weight, and body composition. Muscle tissue burns more calories at rest than fat tissue, which is why people with more muscle have higher BMRs.

This calculator uses the Mifflin-St Jeor equation, published in 1990 and widely considered the most accurate formula for estimating BMR in the general population — more precise than the older Harris-Benedict equation.

The Mifflin-St Jeor Equation

The formulas, where weight is in kg, height is in cm, and age is in years:

To get TDEE (your actual daily calorie needs), multiply BMR by your activity factor: 1.2 for sedentary, up to 1.9 for extremely active. This accounts for the energy cost of movement beyond basic survival functions.

The 3,500 Calorie Rule

One pound of body fat stores approximately 3,500 calories of energy. The long-standing rule of thumb is that a 500-calorie daily deficit will result in roughly one pound of weight loss per week (500 cal × 7 days = 3,500 cal).

This rule is a useful starting point but an imperfect model. In reality, weight loss slows over time because your BMR decreases as you lose weight — you are literally smaller and need fewer calories to maintain. Metabolic adaptation also occurs, making sustained deficits harder.

Most evidence-based dietitians recommend a 250–500 calorie daily deficit for sustainable fat loss, aiming for 0.5–1% of body weight per week — aggressive enough to make progress, slow enough to preserve muscle and metabolic health.

Why Activity Level Matters So Much

The difference between sedentary and very active can be 700–1,200 calories per day — more than the caloric content of an entire extra meal. This is why physical activity is so important for body composition and metabolic health.

Most people underestimate their activity level. "Sedentary" means a desk job with essentially no intentional exercise. If you walk 30 minutes a day, you are at least lightly active. Three gym sessions per week puts you in the moderate category.

Note that TDEE estimates have significant individual variability — typically ±10–15%. Track your actual food intake and body weight for 2–3 weeks to calibrate your personal TDEE more accurately than any formula can.

Macronutrients: Beyond Calories

Total calories determine whether you gain, lose, or maintain weight. But macronutrient composition — how those calories are divided among protein, carbohydrates, and fat — significantly affects body composition, satiety, and performance.

• •Protein (4 cal/g): Essential for muscle preservation and growth. Target 0.7–1g per pound of body weight, especially in a deficit.
• •Carbohydrates (4 cal/g): Primary fuel for high-intensity exercise and brain function. Whole food sources provide fiber and micronutrients.
• •Fat (9 cal/g): Necessary for hormone production, vitamin absorption (A, D, E, K), and satiety. Minimum ~20% of total calories.

Practical Tips for Hitting Your Calorie Target

• •Track for 2 weeks: Use an app like MyFitnessPal or Cronometer to accurately measure your current intake before changing anything. Most people are off by 30–50%.
• •Prioritize protein and volume: High-protein, high-fiber foods are more satiating per calorie. Vegetables, lean meats, legumes, and eggs keep you full on fewer calories.
• •Be consistent, not perfect: A 200-calorie daily deficit maintained for a year beats an aggressive 1,000-calorie deficit that is abandoned after 3 weeks.
• •Recalculate regularly: Recalculate your TDEE every 10–15 lbs of weight change, as your caloric needs shift with body weight.