Adult BMI categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity (class 1) |
| 35.0 – 39.9 | Obesity (class 2) |
| 40.0 and above | Obesity (class 3) |
What BMI tells you
BMI is weight (kg) divided by height squared (m²). It is a quick population-level screening tool for weight status, but it cannot tell muscle from fat or show where fat is stored. A very muscular person may read "overweight" while being lean.
Important caveats
These ranges apply to most adults. They differ for children and teens (who use age- and sex-specific percentiles), some ethnic groups (lower thresholds may apply), pregnant people, athletes, and the elderly. Pair BMI with a body-fat estimate and waist measurement for a fuller picture.