Body measurements Health Calculators

Body Mass Index (BMI) for Kids

BMI Calculator for Kids

BMI calculator for kids, a tool that works as both a BMI calculator for girls and a BMI calculator for boys.

BMI is a measurement of the body’s mass that takes into account not just the weight of a person, but also their height. The acronym BMI stands for Body Mass Index and it is very easy to calculate on your own, though it’s even easier if you use our BMI calculator for kids. If you insist on doing it on your own, here is the BMI formula:

BMI = weight / height²

where both weight and height should be in SI units (i.e.: kg and m).

This then makes kg/m² the units of BMI. This is not the only units it is possible to use, but are the most widespread, even in the USA. This is due to these units being used by the World Health Organization (WHO) for setting the limits and acceptable ranges of BMI.

How is BMI used with children and teens?

For children and teens, BMI is not a diagnostic tool. Instead it is used to screen for potential weight and health-related issues. If children have a high BMI for their age and sex, a health care provider may perform further assessments to determine if excess fat is a problem. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings. The American Academy of Pediatrics recommends using BMI to screen for overweight and obesity in children beginning at 2 years old. For children under the age of 2 years old, consult the World Health Organization (WHO) standards.

Children’s BMI Calculator

Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters. It is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems.

For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age. In children, a high amount of body fat can lead to weight-related diseases and other health issues. Being underweight can also put one at risk for health issues.

A high BMI can indicate high body fatness. BMI does not measure body fat directly, but BMI is correlated with more direct measures of body fat.

The BMI-for-age percentile growth charts are the most commonly used indicator to measure the size and growth patterns of children and teens in the United States. BMI-for-age weight status categories and the corresponding percentiles were based on expert committee recommendations and are shown in the following table.

BMI-for-age weight status categories and the corresponding percentiles

Weight Status Category Percentile Range
Underweight Less than the 5th percentile
Normal or Healthy Weight 5th percentile to less than the 85th percentile
Overweight 85th to less than the 95th percentile
Obese Equal to or greater than the 95th percentile

What are the health consequences of obesity during childhood?

Health risks now
  • Childhood obesity can have a harmful effect on the body in a variety of ways.
    • High blood pressure and high cholesterol, which are risk factors for cardiovascular disease (CVD). In one study, 70% of obese children had at least one CVD risk factor, and 39% had two or more.
    • Increased risk of impaired glucose tolerance, insulin resistance and type 2 diabetes.
    • Breathing problems, such as sleep apnea, and asthma.
    • Joint problems and musculoskeletal discomfort.
    • Fatty liver disease, gallstones, and gastro-esophageal reflux (i.e., heartburn).
    • Psychological stress such as depression, behavioral problems, and issues in school.
    • Low self-esteem and low self-reported quality of life.
    • Impaired social, physical, and emotional functioning.
Health risks later
  • Obese children are more likely to become obese adults. Adult obesity is associated with a number of serious health conditions including heart disease, diabetes, and some cancers.
  • If children are overweight, obesity in adulthood is likely to be more severe.

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