The adult BMI ranges
- Under 18.5 — underweight
- 18.5 to 24.9 — healthy weight
- 25 to 29.9 — overweight
- 30 and over — obesity
These bands are a screening tool used across large populations — not a personal diagnosis.
How BMI is calculated
BMI = weight (kg) ÷ height (m)². For example, 70 kg at 1.75 m = 70 ÷ 3.06 ≈ 22.9, which is in the healthy range.
Why BMI has limits
BMI doesn’t separate muscle from fat or show where fat is stored, so athletes can read as “overweight”. It can also read differently by age and ethnicity. Pair it with your waist-to-height ratio for a fuller picture.