WHO BMI categories (adults)
- Below 18.5: underweight
- 18.5 – 24.9: healthy weight
- 25 – 29.9: overweight
- 30 – 34.9: obesity class I
- 35 – 39.9: obesity class II
- 40 and above: obesity class III
Some Asian countries use lower cut-offs, because health risks rise at lower BMI in Asian populations. Korea, for example, treats 23 as overweight and 25 as obese.
The formula
BMI = weight (kg) ÷ height (m)², or in imperial units 703 × weight (lb) ÷ height (in)². At 175 cm and 72 kg, BMI is 72 ÷ 1.75² ≈ 23.5.
Limits of BMI
BMI does not tell muscle from fat, so it can overstate fat in muscular people and understate it in older adults. Waist size and body-fat percentage add useful context. This result is for information only and is not a diagnosis; children and teenagers need age-specific charts.