BMI Calculator
Calculate your Body Mass Index instantly with gender, age, height, and weight
How to Use the BMI Calculator
BMI (Body Mass Index) is a simple measure that uses your height and weight to estimate whether you are underweight, normal weight, overweight, or obese. Enter your gender, age, height, and weight to instantly calculate your BMI and see which category you fall into.
BMI Formula
Metric: BMI = weight(kg) ÷ height(m)². Example: 70 kg, 175 cm → BMI = 70 ÷ (1.75)² = 22.9. Imperial: BMI = [weight(lbs) ÷ height(in)²] × 703.
BMI Classification Standards
WHO International: Underweight < 18.5 / Normal 18.5–24.9 / Overweight 25–29.9 / Obese ≥ 30.
WHO Asia-Pacific (Korea, Japan, China, etc.): Underweight < 18.5 / Normal 18.5–22.9 / Overweight 23–24.9 / Obese 25–29.9 / Severely Obese ≥ 30. Asian populations carry more body fat at the same BMI compared to Western populations.
Age Considerations
BMI is most accurate for adults aged 18–64. For children and teenagers, BMI-for-age percentiles should be used. For older adults (65+), the relationship between BMI and health outcomes differs from younger adults.
Limitations of BMI
BMI does not distinguish between muscle and fat. Athletes with high muscle mass may be classified as overweight or obese, while individuals with low muscle mass may appear normal despite having excess body fat. Waist circumference and body fat percentage provide additional context.