BMI Calculator
Calculate your Body Mass Index (BMI) and understand your weight category
BMI Categories
Underweight: BMI less than 18.5
Normal weight: BMI 18.5 to 24.9
Overweight: BMI 25 to 29.9
Obesity (Class 1): BMI 30 to 34.9
Obesity (Class 2): BMI 35 to 39.9
Obesity (Class 3): BMI 40 or higher
Note: BMI is a screening tool, not a diagnostic tool. Factors like muscle mass, age, sex, ethnicity, and body composition are not accounted for in BMI calculations. Consult a healthcare provider for a complete health assessment.
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a value derived from a person's weight and height. It is widely used as a general indicator of whether a person has a healthy body weight for their height. Specifically, the value is used to categorize whether a person is underweight, normal weight, overweight, or obese.
How BMI is Calculated
BMI is calculated by dividing a person's weight in kilograms by the square of their height in meters. The formula is: BMI = weight (kg) / [height (m)]². For people who use the imperial system, the formula is: BMI = 703 × weight (lb) / [height (in)]².
BMI Categories
According to the World Health Organization (WHO), BMI values are categorized as follows:
- Underweight: BMI less than 18.5
- Normal weight: BMI between 18.5 and 24.9
- Overweight: BMI between 25 and 29.9
- Obesity (Class 1): BMI between 30 and 34.9
- Obesity (Class 2): BMI between 35 and 39.9
- Obesity (Class 3): BMI 40 or greater
Limitations of BMI
While BMI is a useful tool for assessing weight status in populations, it has limitations when applied to individuals. BMI doesn't distinguish between weight from muscle and weight from fat, so very muscular individuals may have a high BMI without excess fat. Additionally, BMI doesn't account for factors like age, sex, ethnicity, and body composition, which can affect the relationship between BMI and health risks.