BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency risk |
| 18.5 – 24.9 | Normal weight | Lowest risk |
| 25.0 – 29.9 | Overweight | Moderate risk |
| 30.0 – 34.9 | Obese Class I | High risk |
| 35.0+ | Obese Class II+ | Very high risk |
BMI Formula
Metric: BMI = weight (kg) / height² (m)
Imperial: BMI = 703 × weight (lbs) / height² (inches)
Frequently Asked Questions
A BMI between 18.5 and 24.9 is considered healthy for most adults. This range is associated with the lowest risk of weight-related health conditions.
BMI has limitations — it doesn't account for muscle mass, age, sex, or fat distribution. Athletes often show "overweight" BMI despite being very healthy. Use it as a screening tool alongside other metrics.
Yes — for children and teens (2–19), BMI is age and sex-specific, expressed as a percentile rather than a fixed range. This calculator is designed for adults 20+.
A BMI of 30 or above is classified as obese. This is further divided into Class I (30–34.9), Class II (35–39.9), and Class III/morbid obesity (40+). Each class carries progressively higher health risks.