⚖️ BMI Calculator
What is BMI?
Body Mass Index (BMI) is a widely used screening tool that estimates body fat based on height and weight. It helps healthcare professionals quickly identify potential weight-related health risks at the population level.
BMI Categories for Adults
| BMI | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk |
| 18.5 – 24.9 | Normal / Healthy Weight | Lowest risk |
| 25.0 – 29.9 | Overweight | Moderate risk |
| 30.0 – 34.9 | Obese (Class I) | High risk |
| 35.0 – 39.9 | Obese (Class II) | Very high risk |
| 40.0 and above | Obese (Class III) | Extremely high risk |
Limitations of BMI
BMI is a population screening tool, not a diagnostic measure. It may overestimate fat in muscular athletes and underestimate it in people with low muscle mass. It also does not account for fat distribution, which matters for health outcomes. Age, sex, and ethnicity can influence how BMI maps to actual health risk.
⚠️ BMI is for informational purposes only. Consult a qualified healthcare provider for personal health and weight management advice.
Frequently Asked Questions
BMI (Body Mass Index) is a number calculated from your height and weight. It's used as a quick screening tool to categorize adults as underweight, normal weight, overweight, or obese. Formula: BMI = weight(kg) ÷ height(m)².
For adults: Under 18.5 = Underweight, 18.5–24.9 = Normal, 25–29.9 = Overweight, 30+ = Obese. These ranges apply to both men and women, though body composition can vary significantly at the same BMI.
BMI is a useful population-level screening tool but has limitations for individuals. It overestimates fat in muscular people and may underestimate it in older adults. It also doesn't indicate where body fat is stored — belly fat carries higher health risks than fat elsewhere.
Metric: BMI = weight(kg) ÷ height(m)². Imperial: BMI = (weight(lbs) × 703) ÷ height(inches)². Example: 70kg, 175cm → BMI = 70 ÷ (1.75)² = 22.9 (Normal weight).
A BMI of 30.0 or above is classified as obese. Obesity is further divided into: Class I (30–34.9), Class II (35–39.9), and Class III or severe obesity (40+). At these levels, the risk of type 2 diabetes, heart disease, and other conditions increases significantly.