BMI, or body mass index, is a measurement that uses height and weight to determine if a person is underweight, a healthy weight, overweight, or obese. It is calculated using a person's height and weight and can indicate future health risks. For adults, BMI ranges are under 18.5 (underweight), 18.5-24.9 (healthy weight), 25-29.9 (overweight), and 30 or higher (obese). For children, BMI is also based on age and sex, and uses BMI percentiles rather than ranges. Easy online or app calculators are available to determine an individual's BMI.

1. BMI
What is BMI?
How do you use BMI?
By Kathryn Kotula, R.D., M.S., M.P.H.

2. Introduction
• BMI – have you heard of it?
• What is it and how do you use it?
What is BMI?
• BMI is an acronym for BODY MASS INDEX

3. What is BMI used for?
• Height/Weight charts – BMI is now used in place of the old
Height/Weight charts
• BMI – health professionals use the BMI to determine is a
person is a healthy weight for their height
• BMI is calculated based on a person’s height and weight
• BMI is a number used to determine one’s level of body fatness

4. How is BMI used as a Measure of
Health?
• BMI is used to screen for weight problems that may lead to
future health problems
• For most people BMI is a reliable indicator of body fatness
• The higher the BMI number, the more body fat a person has.

5. Is BMI always a reliable indicator of
Body Fatness?
• Although BMI is a reliable indicator of body fatness for most
people there is an exception:
• Athletes: those who are very physically fit, may have a high
BMI due to a lot of muscle mass but not due to a high level of
body fatness.

6. How do you calculate BMI for
adults
• BMI can be calculated using the formula:
Formula: weight (kg) / [height (m)]2
• BMI calculator: an easier method is to use a BMI calculator.
• The adult BMI calculator is used to determine the BMI for people
20 years of age and over.
• Numerous BMI calculators are available.
• One popular BMI is at the CDC.gov website. You can choose the
Adult BMI calculator or the Child and Teen BMI calculator
• http://www.cdc.gov/healthyweight/assessing/bmi/
• OR you can down load an App from iTunes that you can use to
calculate BMI using a Smartphone.
• A popular BMI calculator App can be downloaded from:
• http://apps.usa.gov/bmi-app.shtml

7. BMI Apps for Your Smartphone
• OR you can down load an App from iTunes that you can use to
calculate BMI using a Smartphone.
• A popular BMI calculator App can be downloaded from:
• http://apps.usa.gov/bmi-app.shtml
• Or download the BMI calculator free App from Itunes at BMI
calculator from Itunes
• You want a BMI calculator that calculates BMI for adults and
for children/teens as the calculation is different.

8. How do you interpret BMI levels
for adults?
• Once you determine a BMI level for an adult, use the chart
below to determine the person’s weight category:
BMI Weight Status
Below 18.5 Underweight
18.5 – 24.9 Normal
25.0 – 29.9 Overweight
30.0 and Above Obese

9. How do you interpret BMI levels
for children?
• For those over 2 years of age and under 20 years of age,
calculating and interpreting BMI levels is different than for an
adult.
• The BMI is calculated from the child’s weight and height, age
and sex.
• BMI percentile: a percentile ranking is also determined. It is
this percentile that is used to evaluate a child’s weight status.
• Like adults, BMI is used to determine if a childe is
underweight, a healthy weight, overweight or obese.

10. BMI Table for Children
• Once a BMI percentile is calculated for a child, then the table
below is used:
Weight Status Category Percentile Range
Underweight Less than the 5th percentile
5th percentile to less than the 85th
Healthy weight
percentile
Overweight 85th to less than the 95th percentile
Equal to or greater than the 95th
Obese
percentile

11. Learning More About BMI
• For more information on BMI, go to www.CDC.gov and type in
“BMI”
• OR use the QR below to take you to the CDC website

12. Summary of BMI
• Body Mass Index (BMI) is the latest tool to assess the amount
of body fatness in a person.
• It is a calculation using a person’s height and weight.
• Health professionals use BMI to determine if one is
underweight, a healthy weight, overweight or obese.
• BMI can provide an indication of weight categories that could
lead to future health problems.
• BMI levels are interpreted differently for adults and children
so different BMI calculators are used.

13. Summary of BMI
• BMI is a relatively new tool to determine if one is
underweight, a healthy weight, overweight or obese.
• BMI for adults is based on height and weight.
• BMI for children is based on height, weight, age and sex.
• The easiest way to calculate BMI is to use a BMI calculator at
CDC.gov or an App.