BMI Calculator

According to the World Health Organization and most health authorities, a BMI between 18.5 and 24.9 is considered within the normal or healthy weight range for adults. A BMI below 18.5 is classified as underweight, 25.0 to 29.9 is considered overweight, and 30.0 or higher falls into the obese category. However, these are general guidelines, and interpretation may vary based on factors like age, ethnicity, body composition, and individual health circumstances.

BMI is a useful screening tool, but it has limitations in assessing individual health. It doesn't distinguish between muscle and fat mass, which means athletic individuals with high muscle mass may have a high BMI despite having low body fat. Similarly, elderly people who have lost muscle mass may have a "normal" BMI despite carrying excess fat. BMI also doesn't account for differences in body composition between ethnicities and doesn't indicate where fat is distributed in the body (central vs. peripheral), which can be important for health risk assessment. For a comprehensive health evaluation, BMI should be considered alongside other measurements like waist circumference, body fat percentage, and assessments of lifestyle factors and medical history.

The standard BMI categories (underweight, normal weight, overweight, and obese) apply to both adult men and women. However, there are natural differences in body composition between the sexes. Women typically have a higher percentage of body fat than men with the same BMI. Some research suggests that health risks may begin at different BMI thresholds for men and women, and for different ethnic groups. Some healthcare providers may use sex-specific or ethnicity-specific BMI charts or consider other factors alongside BMI when evaluating an individual's health status.

There's no strict rule about how often to calculate your BMI, but checking it periodically can help you monitor changes in your weight status. For most adults maintaining a stable weight, checking BMI once or twice a year is sufficient. If you're actively trying to lose or gain weight, you might check more frequently, perhaps monthly, to track your progress. However, it's important not to become fixated on the number. BMI is just one health indicator, and small fluctuations are normal. Focus on overall trends rather than day-to-day changes, and always consider BMI alongside other aspects of your health like energy levels, physical fitness, sleep quality, and other health markers.