Body Mass Index Calculator
WHO-based BMI analysis with BMI Prime, Ponderal Index & healthy weight range
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Understanding Your BMI
BMI (Body Mass Index) is a measure of body leanness or corpulence based on height and weight. It is widely used as a general indicator of healthy body weight, though it does not measure body fat directly.
WHO BMI Classification for Adults (20+)
| Classification | BMI Range (kg/m²) | BMI Prime |
|---|---|---|
| Severe Thinness | < 16 | < 0.64 |
| Moderate Thinness | 16 – 17 | 0.64 – 0.68 |
| Mild Thinness | 17 – 18.5 | 0.68 – 0.74 |
| Normal | 18.5 – 25 | 0.74 – 1.00 |
| Overweight | 25 – 30 | 1.00 – 1.20 |
| Obese Class I | 30 – 35 | 1.20 – 1.40 |
| Obese Class II | 35 – 40 | 1.40 – 1.60 |
| Obese Class III | > 40 | > 1.60 |
BMI Formulas
US Units: BMI = 703 × weight(lbs) ÷ height²(in)
Metric: BMI = weight(kg) ÷ height²(m)
BMI Prime: BMI ÷ 25
Ponderal Index: weight(kg) ÷ height³(m)
Risks of Being Overweight
High blood pressure & cardiovascular disease
Type II diabetes & insulin resistance
High LDL cholesterol & triglycerides
Sleep apnea & breathing difficulties
Increased cancer risk (breast, colon, kidney)
Osteoarthritis & joint pain
Risks of Being Underweight
Malnutrition & vitamin deficiencies
Osteoporosis & bone weakness
Weakened immune system
Hormonal imbalances & anemia
Limitations of BMI
BMI does not account for muscle mass, bone density, age, sex, or ethnicity. Athletes may have a high BMI due to muscle. Older adults may have more body fat at the same BMI. Always consult a healthcare professional for a complete health assessment.