BMI Calculator
Enter your weight and height to calculate your Body Mass Index.
Measurements
Result
BMI
24.2
Normal weight
Healthy BMI range: 18.5 – 24.9
Disclaimer: BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, age, or fat distribution. Consult a healthcare professional for a full health assessment.
What is BMI?
Body Mass Index (BMI) is a simple numerical value calculated from your weight and height. It was developed in the 1830s by Belgian mathematician Adolphe Quetelet and has since become the most widely used screening tool for classifying weight categories in adults. Health organisations such as the WHO and CDC use BMI as a first-pass indicator of potential weight-related health risks.
Despite its widespread use, BMI is a population-level tool with known limitations at the individual level. It does not measure body fat directly and cannot distinguish between muscle and fat mass. A highly muscular athlete may have a high BMI without excess body fat, while a sedentary person with low muscle mass may have a normal BMI despite unhealthy fat levels.
How is BMI calculated?
Metric: BMI = weight (kg) ÷ height (m)²
Imperial: BMI = 703 × weight (lbs) ÷ height (in)²
BMI categories (WHO)
| BMI | Category | Notes |
|---|---|---|
| < 18.5 | Underweight | May indicate malnutrition, an eating disorder, or other health conditions. |
| 18.5 – 24.9 | Normal weight | Associated with the lowest risk of weight-related health issues for most adults. |
| 25.0 – 29.9 | Overweight | Increased risk of cardiovascular disease, type 2 diabetes, and hypertension. |
| ≥ 30.0 | Obese | Significantly elevated risk of serious health conditions including heart disease and stroke. |
Limitations of BMI
BMI does not account for age, sex, ethnicity, muscle mass, or where fat is distributed on the body. Older adults naturally lose muscle and gain fat, so their health risk may be underestimated. Athletes with high muscle mass often register as overweight or obese despite low body fat. For a more complete picture, consider pairing BMI with waist circumference measurements or a body fat assessment.