BMI Calculator

Body mass index with WHO categories, metric or US units

Units

BMI formula

BMI = weight (kg) ÷ height (m)². In US units, BMI = 703 × weight (lb) ÷ height (in)². For example, 72 kg at 175 cm gives 72 ÷ 1.75² = 23.5, which is a healthy weight.

WHO adult BMI categories

Asian adults face higher health risks at a lower BMI, so lower cut-offs are often used (South Korea, for example, defines obesity as a BMI of 25 or more). These categories are for adults aged 20 and over; children and teens are assessed with age- and sex-specific percentiles.

Frequently asked questions

What is a healthy BMI?

For adults, the World Health Organization classifies a BMI of 18.5 to 24.9 as a healthy weight, 25 to 29.9 as overweight and 30 or above as obesity.

Are the cut-offs different for Asian adults?

Yes. Because health risks rise at a lower BMI in many Asian populations, the WHO suggests lower action points for Asian adults, and South Korea treats a BMI of 25 or above as obesity.

Is BMI accurate for everyone?

BMI does not distinguish muscle from fat, so it can overstate risk for athletes and understate it for older adults. Waist circumference and a check-up with a doctor give a fuller picture.