BMI is calculated by dividing your weight in kilograms by your height in meters squared: BMI = weight (kg) ÷ height (m)². For example: a person weighing 70 kg and 1.75 m tall has BMI = 70 ÷ (1.75 × 1.75) = 22.9.

A normal BMI is between 18.5 and 24.9. Underweight is below 18.5, overweight is 25–29.9, and obese is 30 or higher. These thresholds are based on WHO recommendations.

Daily calories are calculated using the Mifflin-St Jeor equation which accounts for weight, height, age and gender. The result shows basal metabolic rate (BMR) multiplied by an activity factor (1.2 for sedentary lifestyle).

BMI is a useful screening tool but has limitations. It does not distinguish between muscle mass and fat mass. Athletes may have a high BMI without being overweight. Use BMI as an indicator, not as a sole diagnostic tool.

A healthy weight range depends on your height. It is calculated as BMI 18.5–25 multiplied by your height in meters squared. The calculator shows your healthy range automatically.