BMI Calculator
Body Mass Index with WHO category — metric and imperial.
How BMI is calculated
BMI = weight (kg) ÷ height (m)². In imperial units: (weight in lb × 703) ÷ height in inches². WHO categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.
What BMI can and can't tell you
BMI is a quick population-level screen, not a diagnosis. It does not distinguish muscle from fat, so athletes often read "overweight" while being lean. Treat it as one signal alongside waist measurement and professional advice.
Frequently asked questions
Is BMI accurate for everyone?
It is less reliable for very muscular people, older adults and children (children use age-adjusted percentile charts instead).
What is a healthy BMI?
The WHO "normal" band is 18.5–24.9, but individual healthy ranges vary — discuss your result with a healthcare professional.