BMI at age 19
Children and teens are compared with others of the same age and sex. BMI is read as a percentile. This page shows how that works at age 19.
How it works
BMI is weight in kilograms divided by height in meters squared. For a child that number is scored against the CDC table. M is the median BMI for the age and sex. L and S set the shape of the spread. The z score and percentile follow from all three. For males at age 19 the 5th, 85th and 95th percentile BMI values are 18.7, 26.4 and 29.7.
Worked example
For a boy aged 19 at 5 ft 10 in and 157 lb, height is 1.7780 m and weight is 71.214 kg. Square the height: 1.7780 × 1.7780 = 3.1613. BMI is 71.214 divided by 3.1613, which is 22.5268. The CDC values are L -1.8351, M 22.501 and S 0.13257. Divide the BMI by M to get 1.001147. Raise that to the power L to get 0.997899. Subtract 1 to get -0.002101. Divide by L × S to get z = 0.009. The 50th percentile falls in the healthy weight band.
At age 19, a boy and a girl each at the CDC median height and the weight that gives the median BMI. The form above is set to the boy.
- Male at median height and weight (5 ft 10 in, 157 lb)
- BMI 22.5, 50th percentile
- Female at median height and weight (5 ft 4 in, 126 lb)
- BMI 21.6, 51st percentile
Common questions
Why does BMI change as a child grows?
BMI usually falls through early childhood and then rises through the teen years. That is normal growth, which is why the chart is built by age. The median BMI for males is 22.5 at age 19.
What should I do if my child is above the 85th percentile?
One reading is not a diagnosis. Raise it with your child's doctor, who can look at growth history and the whole picture. The 85th percentile BMI for males at age 19 is 26.4.
Which ages does this calculator cover?
It covers ages 2 to 20, the range of the CDC growth charts. For adults over 20 use the adult BMI calculator. This page reads the CDC male table at 228.5 months.
Why does a child BMI use percentiles and not the adult bands?
Children grow, and a healthy BMI changes with age and differs between males and females. A percentile shows where a child sits among others of the same age and sex. At age 19 the median BMI is 22.5 for males and 21.6 for females, and the example boy sits at the 50th percentile.
What do the percentile bands mean?
Below the 5th percentile is underweight. From the 5th up to the 85th is a healthy weight. From the 85th up to the 95th is overweight. The 95th and above is obesity. At age 19 the 5th, 85th and 95th percentile BMI values for males are 18.7, 26.4 and 29.7.