Body Mass Index

The BMI (defined as weight in kg/[height in m]2) provides a measure of relative weight, adjusted for height. This allows comparisons within and between populations. The healthy range for the BMI is between 18.5 and 24.9. Individuals with a BMI between 25 and 29.9 are considered overweight, those with a BMI ≥30 are defined as obese, and a BMI >40 is considered severely (morbidly) obese (Fig. 1). These cutoffs are based on studies examining the relationship of BMI to premature death and are similar in men and women. Nearly two thirds of U.S. adults are overweight, and more than one third of those are obese. Children with a BMI-for-age above the 95th percentile are considered obese.

Figure 1:  To use this body mass index (BMI) chart, find height in the left-hand column. Move across the row to weight. Height and weight intersect at the individual’s BMI. [Note: To calculate BMI using pounds and inches, use BMI = weight in pounds/(height in inches)² × 703. Anyone >100 pounds overweight is considered morbidly obese.]