Finding Out Your Body Mass Index (BMI)

What is body mass index?

Learning how much you should weigh is not a simple matter of looking at a height-weight chart. It also includes knowing the amount of bone, muscle, and fat in your body. The amount of fat is the most important measurement.

A good way to know how much fat you have is the body mass index (BMI). It is not a perfect measure. But it gives a fairly good idea of how much of your body is fat. Your body may vary based on your age or ethnicity. The most accurate way to find your BMI is to have an exam by your healthcare provider. Your provider can also talk with you about your risks for health problems. They can give you advice for diet and exercise to get to a healthy BMI.

Calculate your BMI using the English formula

BMI can be calculated using pounds and inches:

BMI = (weight in pounds x 703) / (height in inches x height in inches)

For example, a person who weighs 165 pounds and is 5 feet 4 inches tall has a BMI of 28:

(165 lbs x 703) / (64 inches x 64 inches) = 28

Calculate your BMI using the metric formula

BMI can be calculated using kilograms and meters:

BMI = weight in kilograms / (height in meters x height in meters)

For example, a person who weighs 99.79 kilograms and is 1.905 meters tall has a BMI of 27.5:

99.79 kg / (1.905 meters x 1.905 meters) = 27.5

What does my BMI mean?

Here is what your number means:

  • BMI below 18.5 is underweight

  • BMI of 18.5 to 24.9 is healthy weight

  • BMI of 25 to 29.9 is overweight

  • BMI of 30 and above is obese

Online Medical Reviewer: Callie Tayrien RN MSN
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Online Medical Reviewer: Steven Kang MD
Date Last Reviewed: 8/1/2023
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