Body Mass Index (BMI) is used as a screening tool to identify possible weight problems in children. BMI is calculated from a person's weight and height.
This calculator can help to determine whether a child is at a healthy weight for his/her height, age and gender. The amounts of body fat, muscle, and bone change with age, and differ between boys and girls. This BMI-calculator automatically adjusts for differences in height, age and gender, making it is one of the best tools for evaluating a growing child's weight.
Keep in mind that BMI is not a diagnostic tool. BMI and BMI-percentile-for-age do not directly measure body fat. Very athletic kids can have a high BMI-for-age due to extra muscle mass, not necessarily excess body fat. As a result, a child may have a high BMI for their age and gender, but to determine if excess fat is a problem, a health care provider would need to perform further tests. Therefore, it's important that children with a BMI-percentile-for-age over the 85th percentile be evaluated by a health professional.
All values must be entered in order to calculate percentiles for BMI, Height and Weight.
Make sure to click the 'Calculate' button or press the 'Enter' key after entering your values.
2 - 20 yrs
A percentile shows the relative position of the child's BMI, Weight or Height among children of the same sex and age.
For example, a boy at the 25th percentile for height is taller than 25% of boys his age. If a girl is at the 40th percentile for height, she is taller than 40% of girls at that same age.
To help put a child's growth into perspective, use the charts below to further compare weight & height
with age- and gender-specific growth charts.
The American Academy of Pediatrics (AAP) and the U.S. Centers for Disease Control and Prevention (CDC) recommend the use of BMI to screen for overweight and obesity in children beginning at 2 years old.
You can read more about BMI and daily energy requirements at the Children's Nutrition Research Center's web site
The tools provided here are based on publicly available data from the National Health and Nutrition Examination Survey (Centers for Disease Control and Prevention, U.S. Department of Health and Human Services).
BMI-for-age weight status categories and their related percentile ranges are shown in the table below.
|BMI for Age - Weight Status Categories|
|A BMI Percentile of:||Suggests that a child is:|
|Less than the 5th percentile||Underweight|
|5th percentile to less than the 85th percentile||Healthy Weight|
|85th to less than the 95th percentile||Overweight|
|Equal to or greater than the 95th percentile||Obese|
Plotting a child's BMI-for-age on the appropriate CDC growth chart can alert parents to early signs that their child is gaining weight too fast, enabling them to help their child avoid developing weight problems by making small changes in their family's diet and physical activity habits. According to Roman Shypailo, a CNRC body composition expert who developed the calculator, parents who plot the calculator results should watch for significant "drifting," either up or down, in their child's BMI-for-age percentile over time.
For example, a 62-pound, 50-inch tall, 8-year-old girl has a BMI of 17.5, which puts her at the 77th percentile for age. This is a healthy weight for her age and her parents should expect future weight gains to keep her BMI-for-age "tracking" along the 77th percentile as she gets older.
However, a BMI-for-age at the 77th percentile could be a 'red flag' for poor diet and/or physical activity habits if it represents an upward drifting of her BMI-for-age percentile, perhaps from the 66th percentile at age 6 to the 70th at age 7 and the 77th at age 8.
This 'early warning' enables parents catch potentially unhealthy changes in a child's weight at an early age, when making changes in diet and exercise to correct the problem are easier.
Individual results, when compared to other children, can be affected by many factors such as the parents' body sizes and the child's level of physical maturity. Thus, this software should not be used for medical diagnostic or treatment purposes. Additionally, the authors and their affiliated institutions are not liable for any damages to users or third parties arising from the use of this software.
This software is protected under international copyright law. Unauthorized duplication or distribution is a violation of copyright. Entering this section of the web site implies acceptance of the conditions stated above.
Shypailo RJ (2020) Age-based Pediatric Growth Reference Charts. Retrieved
from the Baylor College of Medicine, Children's Nutrition Research Center, Body Composition
Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, Flegal KM, Guo SS, Wei R, Mei Z, Curtin LR, Roche AF, Johnson CL. CDC growth charts: United States. Adv Data 2000:1–27.
Flegal KM, Cole TJ. Construction of LMS parameters for the Centers for Disease Control and Prevention 2000 growth chart. National health statistics reports; no 63. Hyattsville, MD: National Center for Health Statistics. 2013.
Flegal KM, Wei R, Ogden CL, Freedman DS, Johnson CL, Curtin LR. Characterizing extreme values of body mass index-for-age by using the 2000 Centers for Disease Control and Prevention growth charts. Am J Clin Nutr 2009;90:1314–20.