BMI Calculator

BMI (Body Mass Index) is a widely used screening tool that estimates body fat based on height and weight. Our free BMI calculator instantly computes your BMI and tells you which category you fall into — underweight, normal weight, overweight, or obese — based on WHO standards.

BMI Formula

BMI = weight (kg) ÷ height² (m²). In imperial: BMI = 703 × weight (lbs) ÷ height² (inches²). Our calculator supports both metric and imperial inputs.

BMI Categories (WHO)

Underweight: BMI below 18.5. Normal weight: BMI 18.5–24.9. Overweight: BMI 25–29.9. Obese Class I: BMI 30–34.9. Obese Class II: BMI 35–39.9. Obese Class III: BMI 40 and above.

Limitations of BMI

BMI does not distinguish between muscle and fat mass. Athletes with high muscle mass may show as overweight despite being very fit. BMI also doesn't account for fat distribution — abdominal fat carries higher health risk than fat elsewhere. Use BMI as one indicator among many, not as a definitive health measure.