EXAMPLE
175 cm and 70 kg gives a BMI of 22.9 (normal weight).
Enter your height and weight to see results.
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How this calculator works
Body Mass Index is a simple ratio of weight to height, used as a quick general screening tool to see where someone falls on a standard weight range. This calculator works in both metric and imperial units, and shows which category the result falls into.
THE MATH BEHIND IT
Metric: weight (kg) ÷ height (m)²
Imperial: (weight (lb) ÷ height (in)²) × 703
A real example
A person who is 175 cm tall and weighs 70 kg:
BMI
70 ÷ (1.75)² =22.9
Category
Normal weight (18.5–24.9)
Common questions
BMI is calculated from height and weight only. It does not distinguish between muscle mass, bone density, or fat distribution, and does not factor in age or sex.
A BMI under 18.5 is classified as underweight, 18.5–24.9 as normal weight, 25–29.9 as overweight, and 30 and above as obese — categories set by the World Health Organization for population-level screening.
BMI ranges were developed primarily using adult population data and can be less accurate for athletes, older adults, and growing children and teens, who use different, age-based charts.