Body mass index is weight divided by height squared: BMI = kg / m². Enter your height in centimeters and weight in kilograms and the result updates live with one decimal. Because Asian populations carry higher metabolic risk at lower BMI, the Chinese standard (WS/T 428-2013) sets stricter cut-offs — overweight starts at 24 and obesity at 28 — while the WHO standard uses 25 and 30. This tool shows both classifications side by side, plus the weight range that would put you in the normal band (BMI 18.5–24) for your height.
BMI is a population-level screening measure: it does not distinguish muscle from fat, so athletes, pregnant women, children and the elderly should not rely on it alone. Everything is calculated locally in your browser — your data is never uploaded.