| Category | BMI Range | Description |
|---|---|---|
| Underweight | Below 18.5 | May indicate malnutrition or other health concerns |
| Normal weight | 18.5 – 24.9 | Associated with the lowest health risks |
| Overweight | 25.0 – 29.9 | Increased risk of heart disease and diabetes |
| Obese (Class I) | 30.0 – 34.9 | High risk of weight-related conditions |
| Obese (Class II) | 35.0 – 39.9 | Very high risk |
| Obese (Class III) | 40.0 and above | Extremely high risk — seek medical advice |
Metric BMI is calculated as: BMI = weight (kg) ÷ height (m)². First convert height from cm to meters by dividing by 100. For example, a person who is 70 kg and 175 cm: height in meters = 1.75 m, BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.86.
A healthy BMI is between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health problems according to the World Health Organization. However, BMI is a screening tool — it does not account for muscle mass, bone density, age, or body fat distribution.
Yes — BMI is the same value regardless of whether you use metric or imperial inputs. The metric formula is weight(kg) ÷ height(m)², while the imperial formula is (weight(lbs) × 703) ÷ height(inches)². Both produce the same BMI value for the same person.