Determining Body Mass Index for Teens
What is body mass index?
Determining how much your teen should weigh isn't a simple matter of looking at an
insurance height-weight chart. It includes considering the amount of bone, muscle,
and fat in their body. The amount of fat is the critical measurement.
A good indicator of how much fat your teen carries is the body mass index (BMI). Although
it's not a perfect measure, it gives an indirect assessment of how much of your teen's
body is composed of fat. BMI is based on weight and height. As a result, it's only
a gauge of body fatness. Two people may have the exact same BMI, yet have different
amounts of actual body fat.
The formulas below apply to adults only. For children and teens ages 2 to 19 years,
the BMI varies by age and sex. An additional step must be done after the BMI has been
determined using one of the formulas below. The BMI-for-age percentile is determined
by comparing your teen's weight to that of other teens of the same age and sex.
In other words, by plotting your child's BMI value into the CDC's BMI-for-age growth chart , you can determine if your child is underweight, within normal range, overweight,
or obese. Or you can easily calculate it from the CDC's online tool .
To calculate an adult's BMI using the English formula
For example, a person who weighs 165 pounds and is 5 feet 4 inches tall has a BMI
of 28. 165 lbs x 703=28(64 inches) x (64 inches).
To calculate an adult's BMI using the metric formula
A BMI between 25 to 29.9 is considered overweight. Anything over 30 is considered
obese. Normal BMI is between 18.5 and 24.9. BMI cut-offs for people of South Asian
descent are different.
BMI can be calculated using pounds and inches. BMI= weight in pounds x 703 (height in inches) x (height in inches)
Multiply your weight in pounds by 703.
Divide that answer by your height in inches.
Divide that answer by your height in inches again.
BMI can be calculated using kilograms and meters. BMI= weight in kilograms (height in meters) x (height in meters)
Your weight in kilograms.
Divided by your height in meters.
Divide that answer by your height in meters again.
For example, a person who weighs 99.79 kilograms and is 1.905 meters tall has a BMI
of 27.5. 99.79 kg=27.5(1.905 meters) x (1.905 meters)