How to Assess Your Body Mass Index (BMI) - dummies

How to Assess Your Body Mass Index (BMI)

By Erin Palinski-Wade

Your body mass index (BMI) is a formula that takes into account your height versus your weight to determine whether you’re at a healthy weight.

Although BMI can be a fairly reliable indicator of body fat in most people, some exceptions exist. For instance, the NFL player (or other top athlete) with a very high level of muscle mass may have an elevated BMI without actually having a high level of body fat.

Although BMI doesn’t measure body fat directly, research has indicated that it does correspond with direct measures of body fat, which include underwater weighing and dual-energy X-ray absorptiometry (DXA). Because it isn’t practical for you or your regular clinician to weigh you underwater or perform a DXA scan, BMI is an easy, inexpensive way to see whether you’re overweight or have a high percentage of body fat.

To determine your BMI, use the chart shown. The numbers on the left-hand side correlate with your height in inches. The numbers within the chart correlate with your body weight in pounds. To determine your BMI, find your height in inches, and then move your finger to the right until you reach your approximate weight in pounds.

After you find where your height and weight intersect, move your finger upward to the top of the chart to see what your BMI is. For instance, if you are 67 inches in height and weigh 185 pounds, your BMI is 29. If your exact weight isn’t listed, simply go to the closest one.


You can also use an online BMI calculator to get your exact BMI. The calculator on the Centers for Disease Control and Prevention (CDC) website is reliable and easy to find. Search for BMI calculator in the search box on the homepage. You may be able to find a BMI calculator app for your smartphone or tablet as well.

BMI has five categories. Your BMI can fall into one of the following categories: underweight, healthy weight, overweight, obese, or morbidly obese. Your goal is to keep your BMI within the healthy weight range, because weighing too much or too little can increase your risk of many health complications.

BMI Categories and Risk
BMI Weight Status Risk
18.5 or less Underweight Increased risk
18.6–24.9 Healthy weight Low risk
25.0–29.9 Overweight Increased risk
30.0–39.9 Obese High risk
40.0 or more Morbid obesity Very high risk

Don’t get too upset or overly confident about your BMI just yet. Even individuals with a healthy BMI can have too much belly fat, so you need to assess your weight and waist in multiple ways.