Height + Weight → Body Mass Index, weight status & ideal weight range
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | < 18.5 | Malnutrition risk |
| Normal weight | 18.5 – 24.9 | Low risk |
| Overweight | 25.0 – 29.9 | Moderate risk |
| Obese Class I | 30.0 – 34.9 | High risk |
| Obese Class II | 35.0 – 39.9 | Very high risk |
| Obese Class III | ≥ 40.0 | Extremely high risk |
Source: World Health Organization (WHO). BMI is a screening tool, not a direct measure of body fat or health. Athletes, elderly, and children may have different ideal ranges.
BMI (Body Mass Index) = weight in kg ÷ height in meters squared. In imperial units: BMI = 703 × weight (lb) ÷ height (inches)². It provides a quick numeric estimate of whether a person's weight is appropriate for their height.
BMI doesn't distinguish between muscle and fat. Athletes often show a "high" BMI despite having low body fat, while sedentary individuals may show "normal" BMI with excess fat. For clinical decisions, consult a healthcare professional.
WHO defines 18.5–24.9 as the normal weight range for adults. Note: for many Asian populations, health risks increase at lower BMIs, so some guidelines recommend 18.5–22.9 as the ideal range.
This calculator uses adult WHO BMI categories. Children and teens require age- and sex-specific BMI percentiles (CDC growth charts). The results here are not appropriate for anyone under 18.