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How to Calculate Your BMI? Body Mass Index Calculator

Body mass index (BMI) is a measurement based on height and weight as it relates to body fat, and can be used to determine how much risk a person has of developing certain health problems because of his or her weight. As a point of reference, someone with a BMI of 27 is approximately 20 percent overweight. The higher the BMI, the greater the risk a person has to develop additional health problems.

Although body mass index is good for most men and women, it does have certain problems:
  1. BMI can be too high and show excess body fat in athletes and muscle builders.
  2. BMI can be too low in elder persons that lost muscle mass.
  3. BMI Calculator should not be used for children and teens, 2 to 18 years old. For more information, visit

Calculate Your BMI

The BMI Calculator is an easy-to-use online tool to help you estimate your body fat. The BMI calculator uses Imperial or Metric measures. To calculate your BMI, enter your height and your weight in the boxes below and then check your body mass index:

BMI Calculator


Body Mass Index Categories

Technically, the BMI scale will place you in one of six categories. The table below lists the BMI categories along with the BMI score associated with each category:

ClassificationBody Mass Index Score
Underweightless than 18.5
Normal Weight18.5 24.9
Overweight25 29.9
Obesity (Class 1)30 34.9
Obesity (Class 2)35 39.9
Extreme Obesity (Class 3)40+

Body Mass Index: Results

Even though the Body Mass Index was developed more than 150 years ago, major health care providers and authorities such as the CDC in the United States or NHS in the United Kingdom still consider it to be a reliable indicator of body fatness for most people.

However, you should be aware that BMI can show you if you are overweight or not but it can't tell you if suffer from excess body fat. The problem is that BMI cannot note the difference between excess fat, muscle, or bones. Still, you can use your BMI result as a starting point for further discussion with your doctor about your weight and general health.