Calorie Calculator

The number of calories your body needs each day depends on four variables: your physical dimensions, your age, your biological sex, and how active you are. This calculator uses the Mifflin-St Jeor equation — the most clinically validated formula for estimating Basal Metabolic Rate (BMR) — and multiplies the result by an activity factor to produce your Total Daily Energy Expenditure (TDEE): the number of calories your body burns on a typical day. TDEE is the foundation of every evidence-based nutrition approach. To lose weight at roughly one pound per week, you create a 500-calorie daily deficit below your TDEE — a rate widely recognized as sustainable without triggering significant muscle loss or metabolic adaptation. To gain weight at a controlled pace, you add 500 calories above TDEE. Maintenance requires matching calorie intake to TDEE. All three targets are displayed alongside your BMR so you can choose the strategy that fits your goal. Activity level has an outsized effect on TDEE: a sedentary office worker and an endurance athlete with identical height, weight, and age can have calorie requirements that differ by 50% or more. Selecting your activity level accurately is therefore the single most important input. This tool is useful for anyone setting calorie targets for weight loss, weight gain, athletic performance, or simply understanding how their metabolism compares across life stages. As weight, age, or activity changes, the estimate should be recalculated — the body's energy requirements shift meaningfully over time.

This calculator applies the Mifflin-St Jeor equation, published in 1990 and consistently rated the most accurate BMR formula for non-obese adults in clinical comparisons. The two formulas differ only by the final constant: Male BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Female BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. For imperial inputs, weight converts as: lbs × 0.453592 = kg, and height converts as: total inches × 2.54 = cm. A 30-year-old male at 170 lbs and 5'10" (70 total inches): weight = 77.11 kg, height = 177.8 cm. BMR = (771.1) + (1111.25) − (150) + 5 = 1,737 calories. BMR is then multiplied by an activity factor to produce TDEE: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), super active (×1.9). At lightly active, TDEE = 1,737 × 1.375 ≈ 2,388 calories. The weight loss targets apply a 500 calorie/day deficit (for 1 lb/week) and 250 calorie/day deficit (for 0.5 lb/week), derived from the commonly cited approximation that one pound of body fat contains approximately 3,500 stored calories. Weight gain adds 500 calories above TDEE.