BMI at age 10
At 10 years old a BMI number only means something next to other children the same age. Use the form for your child, or read the worked example below.
How it works
First the page works out BMI: weight in kilograms divided by height in meters squared. Then it reads L, M and S from the CDC table for this age and sex. It finds z as ((BMI divided by M) to the power L minus 1) divided by (L times S) and turns z into a percentile. For males at age 10 the median is M 16.646.
Worked example
Convert first: 4 ft 7 in is 139.7 cm and 72 lb is 32.659 kg. Square the height: 1.3970 × 1.3970 = 1.9516. Divide 32.659 by 1.9516 to get 16.7345. Look up the male row for age 10: L -2.7656, M 16.646 and S 0.12011. Divide 16.7345 by 16.646 to get 1.005317. Raise that to the power -2.7656 to get 0.985441. Subtract 1 to get -0.014559. Divide by -2.7656 × 0.12011 to get z = 0.044. That is the 52nd percentile, in the healthy weight band.
At age 10, 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 (4 ft 7 in, 72 lb)
- BMI 16.7, 52nd percentile
- Female at median height and weight (4 ft 6 in, 70 lb)
- BMI 16.9, 50th percentile
Common questions
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 10 the median BMI is 16.6 for males and 16.9 for females, and the example boy sits at the 52nd 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 10 the 5th, 85th and 95th percentile BMI values for males are 14.2, 19.4 and 22.2.
What is the median BMI at age 10?
On the CDC chart the median is 16.6 for males and 16.9 for females at age 10. The example BMI of 16.7 is 0.1 away from the male median of 16.6.
Does BMI show body fat in a child?
Only roughly. BMI uses height and weight. A muscular child can score high. A doctor looks at growth over time as well as the number. A BMI of 16.7 for this boy at age 10 says nothing about how much of the 72 lb is muscle.
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 16.6 at age 10.