BMI Calculator
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a screening tool used to identify possible weight problems for adults. It is calculated by dividing a person's weight in kilograms by the square of their height in meters ($ kg/m^2 $). While BMI is not a direct measure of body fat, it correlates with direct measures of body fat, such as underwater weighing and dual energy x-ray absorptiometry (DXA).
The Formula
The standard formula used in this calculator is:
BMI Categories
- Underweight: BMI is less than 18.5
- Normal weight: BMI is 18.5 to 24.9
- Overweight: BMI is 25 to 29.9
- Obese: BMI is 30 or more
Why It Matters
Maintaining a BMI within the normal range helps reduce the risk of serious health conditions such as type 2 diabetes, heart disease, and high blood pressure. However, BMI has limitations—it does not account for muscle mass, bone density, or overall body composition. Athletes with high muscle mass may be classified as overweight despite having low body fat.
Frequently Asked Questions
Is BMI accurate for children?
No, BMI for children and teens is interpreted differently. While the calculation formula is the same, the result is compared against percentiles for children of the same age and sex.
Does muscle weigh more than fat?
Technically, a pound of muscle weighs the same as a pound of fat, but muscle is much denser. This means a muscular person may have a high BMI but be perfectly healthy.