Calculate your daily calorie needs using three BMR formulas (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle). Get TDEE by activity level, goal-based calorie targets for weight loss, maintenance, or muscle gain, and a full macro split breakdown.
Enter your age, sex, height, and weight. Choose imperial (lbs/inches/ft) or metric (kg/cm). Optionally enter body fat percentage to enable the Katch-McArdle lean-mass formula.
Choose your activity level from sedentary to very active. Then select your goal: lose weight (deficit), maintain weight, or gain muscle (surplus). The calorie target adjusts automatically.
Your BMR, TDEE, and goal calories are shown from all three formulas. A macro breakdown shows suggested protein, carbohydrate, and fat targets in grams and calories.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain vital functions — breathing, circulation, cell production, and organ function. It accounts for approximately 60–70% of total daily calorie expenditure. BMR is influenced by body size, muscle mass, age, and sex.
Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. It represents the total calories you burn each day including all physical activity. Eating at your TDEE maintains your current weight. Eating below it creates a calorie deficit for weight loss; above it creates a surplus for muscle gain.
Mifflin-St Jeor (1990) is considered most accurate for most people — studies show it predicts resting metabolic rate within 10% for 82% of individuals. Harris-Benedict (1919, revised 1984) tends to overestimate slightly. Katch-McArdle is most accurate when you know your lean body mass, as it directly accounts for muscle tissue which drives metabolism.
A moderate deficit of 300–500 calories per day is recommended for sustainable fat loss of 0.3–0.5 kg (0.5–1 lb) per week. A 500–750 deficit targets 0.5–0.75 kg per week. Avoid deficits below 1200 kcal/day for women and 1500 kcal/day for men as these risk nutrient deficiencies and muscle loss.
A lean bulk surplus of 200–300 calories per day supports muscle gain while minimising fat gain. A traditional bulk uses 400–500 extra calories. Beginners can gain muscle at maintenance; experienced lifters need a surplus. Combined with adequate protein (1.6–2.2g/kg) and progressive training, a modest surplus optimises body recomposition.
Activity multipliers: Sedentary (desk job, no exercise) × 1.2. Lightly active (1–3 days exercise/week) × 1.375. Moderately active (3–5 days/week) × 1.55. Very active (6–7 hard workouts/week) × 1.725. Extra active (physical job + daily training) × 1.9. Most people overestimate their activity level — when in doubt, choose one level lower.
