Body Mass Index Calculator For Children and Teenagers

Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 2010/12/27 - Updated: 2024/09/26
Publication Type: Conversion, Calculation
Topic: Medical Calculators and Charts - Publications List

Page Content: Synopsis - Introduction - Main

Synopsis: Calculate the BMI measurement of your child or children using our online Body Mass Index calculator for children aged 1 to 20 years.

Why it matters: The BMI calculator for children and teens is particularly useful because it takes into account age and sex-specific factors, which are crucial for accurately assessing body fat in young individuals. Unlike adult BMI calculations, which use a standard formula, children's BMI needs to be interpreted differently as the amount of body fat changes with age and varies between boys and girls. This specialized calculator helps parents and healthcare providers determine if a child's weight is appropriate for their height and age, allowing for early identification of potential weight issues. By comparing a child's BMI to percentile rankings, it provides insight into how the child's measurements compare to those of their peers, which can be valuable for monitoring growth patterns and overall health - Disabled World (DW).

Introduction

So What Exactly is Body Mass Index (BMI)?

The body mass index (BMI), or Quetelet index, is defined as a value derived from the mass (weight) and height of an individual. The BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m2, resulting from weight in kilograms and height in meters. If pounds and inches are used, a conversion factor of 703 (kg/m2)/(lb/in2) must be applied. When the term BMI is used informally, the units are usually omitted. A high BMI can be an indicator of high body fatness. BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual.

Main Item

Simply put, BMI is a calculation that uses height and weight measurements to calculate how much body fat a person has. Doctors often use a BMI calculation to determine if a child's weight is appropriate for their height and age. The Child BMI calculator below determines if your child is at a healthy weight for their age (up to 20 years of age), simply enter the required information and calculate their BMI level. You can also check your child's Height to Weight Ratio and Infant Growth Percentile

Adult BMI Calculator

NOTE: For Adult male and female BMI measurements you will need to enter your information into our Body Mass Index Calculator for Adults. In addition you may wish to try our Height to Weight Ratio Chart to measure an average adult's height/weight ratio.

Child Body Mass Index Calculator
Enter the following data
Gender of the child
Age of the child	years
Height
Weight
Results
BMI (kg per meter square)
BMI percentile
BMI as a multiple of the mean BMI
Automatic recalculation
AllNutritionals.com

It is important to have your doctor perform regular BMI measurements for your child so the doctor can discuss the results with you.

The BMI Calculation Formula

Body Mass Index is calculated the same way for both adults and children. The calculation is based on the following formulas:

Measurement Units - Formula and Calculation
Kilograms and Meters or Centimeters Formula: weight (kg) / [height (m)]² With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, divide height in centimeters by 100 to obtain height in meters. Example: Weight = 68 kg, Height = 165 cm (1.65 m) Calculation: 68 A- (1.65)² = 24.98
Pounds and Inches Formula: weight (lb) / [height (in)]² x 703 Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703. Example: Weight = 150 lbs, Height = 5'5" (65") Calculation: [150 A- (65)²] x 703 = 24.96

Measurement Units - Formula and Calculation

Kilograms and Meters or Centimeters

Formula: weight (kg) / [height (m)]²

With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, divide height in centimeters by 100 to obtain height in meters.

Example: Weight = 68 kg, Height = 165 cm (1.65 m)

Calculation: 68 A- (1.65)² = 24.98

Pounds and Inches

Formula: weight (lb) / [height (in)]² x 703

Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703.

Example: Weight = 150 lbs, Height = 5'5" (65")

Calculation: [150 A- (65)²] x 703 = 24.96

BMI, Height, and Weight Percentiles

According to the United States CDC National Center for Health Statistics BMI, height, and weight percentiles show how your child compares to other children. For example, if you are 40th percentile in height, that means that you are taller than 40 out of 100 typical children of the same age and sex. If you are 70th percentile in weight that means your child is heavier than 70 out of 100 kids.

BMI Facts

BMI can be used for population assessment of overweight and obesity. BMI is generally regarded as a satisfactory tool for measuring whether sedentary individuals are underweight, overweight or obese with various exceptions, such as: athletes, children, the elderly, and the infirm.
BMI is proportional to mass and inversely proportional to the square of the height. So, if all body dimensions double, and mass scales naturally with the cube of the height, then BMI doubles instead of remaining the same. This results in taller people having a reported BMI that is uncharacteristically high, compared to their actual body fat levels.
BMI is interpreted differently for children and teens, even though it is calculated using the same formula as adult BMI. Children and teen BMI needs to be age and sex-specific because the amount of body fat changes with age and the amount of body fat differs between girls and boys.
Obesity among 2- to 19-year-olds is defined as a BMI at or above the 95th percentile of children of the same age and sex in this 1963 to 1994 reference population. For example, a 10-year-old boy of average height (56 inches) who weighs 102 pounds would have a BMI of 22.9 kg/m2. This would place the boy in the 95th percentile for BMI - meaning that his BMI is greater than that of 95% of similarly aged boys in this reference population - and he would be considered to have obesity.
A BMI that is less than the 5th percentile is considered underweight and above the 95th percentile is considered obese. Children with a BMI between the 85th and 95th percentile are considered to be overweight.
Recent studies in Britain have indicated that females between the ages 12 and 16 have a higher BMI than males of the same age by 1.0 kg/m2 on average.
BMI generally overestimates adiposity on those with more lean body mass (e.g., athletes) and underestimates excess adiposity on those with less lean body mass.
Is BMI an Accurate Indicator of Body Fat? - Research reveals Body Mass Index, which has always been considered the standard for indicating how much body fat in the body, might not be as accurate as originally thought.

Disabled World also provides a number of informative articles and information relating to Childhood Obesity

Author Credentials: Ian was born and grew up in Australia. Since then, he has traveled and lived in numerous locations and currently resides in Montreal, Canada. Ian is the founder, a writer, and editor in chief for Disabled World. Ian believes in the Social Model of Disability, a belief developed by disabled people in the 1970s. The social model changes the focus away from people's impairments and towards removing barriers that disabled people face daily. To learn more about Ian's background, expertise, and achievements, check out his bio.