BMI Calculator
Calculate your Body Mass Index and find out if your weight is healthy for your height.
What is BMI?
Body Mass Index (BMI) is a measure of body fat based on a person's weight and height. It is used by the World Health Organisation (WHO) as a health indicator for adults over 18. A BMI in the normal range (18.5–24.9) is statistically associated with lower risks of cardiovascular disease, type 2 diabetes and other chronic conditions.
| BMI | Category | Interpretation |
|---|---|---|
| < 16 | Severe underweight | |
| 16 – 18.4 | Underweight | |
| 18.5 – 24.9 | Normal weight | |
| 25 – 29.9 | Overweight | |
| 30 – 34.9 | Obesity class I | |
| 35 – 39.9 | Obesity class II | |
| ≥ 40 | Obesity class III |
Source: World Health Organization (WHO), 2000.
How is BMI calculated?
BMI, or Body Mass Index, is obtained by dividing weight in kilograms by height in meters squared. It is the WHO’s standard formula for classifying adult body weight and is widely used in epidemiology due to its simplicity. It is also known as the Quetelet index, in honor of the Belgian statistician who developed it in the 19th century.
Formula
BMI = Weight (kg) ÷ Height² (m)BMI = [Weight (lb) ÷ Height² (in)] × 703
⚠️ Limitations
BMI does not distinguish between muscle mass and body fat. A very muscular person may have an overweight BMI without excess fat, while someone with low muscle mass may have a normal BMI but a high body fat percentage. It also does not consider fat distribution. For a more complete assessment, combine it with waist‑to‑height ratio or body fat percentage.