BMI is body weight divided by a power of height, usually (height)2, which is said to be independent of stature. Calculations based on values for ideal body weight suggest that BMIs for normal men and women should be in the range of 18.5 to 25 kg/m2. Indeed, this range roughly corresponds to the 10th to 75th percentile values recorded from adult individuals. For infants and children, average BMI values change with age, from 13 kg/m2 at birth, to a peak of 18 at about 1 year, a nadir of 15 at about age 6 years, and then a rise to adult values during adolescence.