BMI Calculator
Calculate your Body Mass Index, BMI category, and daily calorie needs (BMR/TDEE).
About the BMI Calculator
Body Mass Index is your weight in kilograms divided by the square of your height in meters: BMI = weight (kg) / height (m)². The result places you into one of four WHO categories — underweight (under 18.5), normal weight (18.5–24.9), overweight (25–29.9), or obese (30+). This calculator also estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, which for men is 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 and for women is the same minus 161 instead of plus 5. Multiplying BMR by an activity multiplier (roughly 1.2 for sedentary up to 1.9 for very active) gives your Total Daily Energy Expenditure (TDEE) — an estimate of the calories you burn in an average day including exercise.
To use it: enter your sex, age, height in centimeters, weight in kilograms, and typical activity level, and every result updates immediately. For example, a 30-year-old male at 175 cm and 75 kg has a BMI of 75 / 1.75² ≈ 24.5 (normal weight), a BMR of roughly 10×75 + 6.25×175 − 5×30 + 5 ≈ 1,724 kcal/day, and at moderate activity (×1.55) a TDEE of about 2,672 kcal/day. Use TDEE as a starting point for a calorie target: eating below it tends to produce weight loss and above it weight gain, adjusted to your goals.