Body Mass Index

Written by Brian Krans | Published on August 15, 2012
Medically Reviewed by George Krucik, MD

Overview

The body mass index (BMI)—also known as the Quetelet index—is a formula used to calculate a person’s body fat content based on his or her weight and height. The World Health Organization (WHO) has used the tool to calculate obesity rates since the 1980s.

One major shortcoming of the test is that it doesn’t take into account frame size or muscularity. Therefore, even a professional athlete may fall into the “obese” range on the index scale because of the weight of muscle on his or her frame.

Why Body Mass Index Is Used

You can calculate your body mass index to determine your body fat content. If your body fat level is too high, you are at risk for diabetes, high blood pressure, stroke, and heart disease.

How to Prepare for Body Mass Index

You will need to know your weight and height. For the most accurate results, use height and weight measurements taken at a doctor’s office or clinic.

The Math: How Body Mass Index Is Calculated

Your body mass index is calculated by dividing your body weight by the square of your height. If your measurements are in inches and pounds, you must multiply the formula by 703.

The Centers for Disease Control and Prevention has a body mass index calculator on its website at www.cdc.gov.

Example from CDC:

Weight = 150 lbs, Height = 5’5" (65")

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

So, an adult who is 5 feet 5 inches tall and weighs 150 pounds has a BMI of 24.96, right on the border between “normal weight” and “overweight.”

The body mass index scale follows these guidelines:

  • Underweight: <18.5
  • Normal weight: 18.5 to 24.9
  • Overweight: 25 to 29.9
  • Obese: >30

Using the Results

If your BMI is greater than 25, ask your doctor about how to lose weight, improve your lifestyle habits, and stay in optimal health.

Sources:

Was this article helpful? Yes No

Thank you.

Your message has been sent.

We're sorry, an error occurred.

We are unable to collect your feedback at this time. However, your feedback is important to us. Please try again later.

More on Healthline

Easy Ways to Conceal an Epinephrine Shot
Easy Ways to Conceal an Epinephrine Shot
Learn how to discreetly carry your epinephrine autoinjectors safely and discreetly. It’s easier than you think to keep your shots on hand when you’re on the go.
Lifestyle Changes to Help Manage COPD
Lifestyle Changes to Help Manage COPD
Leading a healthy lifestyle can make a big difference in your COPD symptoms. Learn more about basic changes that will make it easier to manage your COPD.
Timeline of an Anaphylactic Reaction
Timeline of an Anaphylactic Reaction
From first exposure to life-threatening complications, learn how quickly an allergy attack can escalate and why it can become life threatening.
Numbness, Muscle Pain and Other RA Symptoms
Numbness, Muscle Pain and Other RA Symptoms
The symptoms of RA are more than just joint pain and stiffness. Common symptoms include loss of feeling, muscle pain, and more. Learn more in this slideshow.
Common Asthma Triggers and How to Avoid Them
Common Asthma Triggers and How to Avoid Them
Learn about some of the most common triggers for asthma, as well as measures you can take to minimize your risk of exposure, symptoms, and flares.
Advertisement
Advertisement
Advertisement