What is BMI or Body Mass Index?

BMI is a screening tool used to identify if an individual is underweight, healthy weight, overweight or obese. It is a measure of body size; it gives us an idea whether a person has the correct weight for height.

BMI or body mass index is defined as weight in kilograms divided by square of body height in meters.
Being overweight in childhood can increase risk for a variety of health conditions like type 2 diabetes, high blood pressure and heart disease as one gets older.
Being underweight can increase the risk of malnutrition, osteoporosis, and anemia.

BMI for children and teens is calculated in the same way as they do for adults, by measuring height and weight with a BMI calculator.

BMI measurements during childhood and adolescence also take age and sex into consideration. Girls and boys develop at different rates and have different amounts of body fat at different ages. To calculate your child’s BMI, follow these steps:

  • Enter child’s age and sex along with his/her height in feet and weight in pounds in BMI calculator to calculate the BMI. This will give you the child’s BMI number.
  • Locate the BMI number and child’s age on a gender-specific BMI-for-age chart. This will indicate whether the child is within a healthy range of weight or is overweight or underweight.

Click on the link below to calculate your child’s BMI.
BMI Calculator for Child and Teen

Shown below are BMI charts for boys and girls to plot the BMI percentile.

BMI Chart - Boys Girls BMI Chart

What do the results mean?

The following categories explain the meaning of the results:

Weight Status/Category Percentile Range
Underweight Below the 5th percentile
Healthy Weight 5th percentile to less than the 85th percentile
Overweight 85th percentile to less than the 95th percentile
Obesity Equal to or greater than the 95th percentile


BMI is not accurate enough to use as a diagnostic tool, but it can screen for potential weight problems in children and adults. If someone has a high or low BMI, your physician might then consider other factors, such as:

  • skin fold thickness measurements, which indicate how much fat is in the body in children and adults
  • evaluations of diet and physical activity
  • discuss any family history of cardiovascular disease and other health problems
  • recommend other appropriate health screenings

Your physician or nutritionist can then make diet and exercise recommendations based on these results.

What are some of health risks of being overweight?
Excess weight can have the following adverse health effects on the body:

  • It increases how hard the heart has to work
  • It raises blood pressure, blood cholesterol and triglyceride levels
  • It lowers high-density lipoprotein (HDL), or good cholesterol levels
  • Hyperlipidemia, which involves high LDL cholesterol, high levels of triglycerides
  • It increases risk for diabetes
  • Sleep apnea and respiratory problems
  • Increased risk of asthma
  • Joint pains
  • Low self-esteem and psychological issues

Dr. Manju Akhand is a board certified pediatrician affiliated with Access Pediatrics. Access Pediatrics has two offices locations, Bolingbrook, Illinois and Berwyn, Illinois. For more information, please call her office at 630-679-1275 or 708-665-3129.

Note: Please keep in mind that this BMI calculator is not meant to serve as a source of clinical guidance and is not intended to be a substitute for professional medical advice. Because BMI is based on weight and height, it is only an indicator of body fatness. Individuals with the same BMI may have different amounts of body fat. Persons may consider seeking advice from their healthcare providers on healthy weight status.

This blog provides general information and discussions about health and nutrition. The information and other content provided in this blog, website or in any linked materials is not a substitute for professional medical expertise or treatment.

If you or any other person has a medical concern, you should consult with your health care provider or seek other professional medical treatment immediately. Never disregard professional medical advice or delay in seeking it because of something that you have read on this blog, website or in any linked materials.


  1. https://www.cdc.gov/healthyweight/bmi/calculator.html