Body Mass Index, or BMI, is a statistical measurement that compares an individual’s height and weight. BMIs are often placed on a chart that helps the individual determine whether they are underweight, normal, overweight, or obese. It is widely used in health care because it is an extremely useful and easy to use calculation. Determining BMI does not require any medical equipment or tests. The only information necessary in order to determine a person's BMI is their height and weight.

While there are a number of difficulties when using BMI, it is very useful to determine a person's potential health risks. Those with high and low BMIs are at a higher risk than those in the normal range for a number of health problems. Knowing a patient's BMI can help a physician to provide proper preventative care and recommend appropriate treatments.

How to Calculate BMI

To find your BMI, divide your weight in kilograms by your height, in meters, squared. The formula should look something like this:

BMI= weight(kg)/height^2 (m^2)

This same formula can be used for US units with a few modification:

BMI= weight(pounds)* 703/ height ^2 (inches^2)

You can also use a standardized chart (like the one listed in the resource section) to help you to determine your BMI.


Interpreting BMI

The following are the typical classifications for BMI:

Under 18.5: underweight
18.5-25: normal
26-29: overweight
30-39: obese
40 and up: morbidly obese

Problems with Using BMI

While BMI can be extremely useful, it also has a number of shortcomings. First, the above categories and calculations can only be used adults. Children are classified on a separate chart.

A second problem is that BMI only takes into account height and weight. The underlying assumption is that the person has a typical amount of muscle. For athletes and other individuals with a large amount of muscle, BMI may classify them as overweight when in fact they are not. Measuring body fat may is a much more exact way to determine if a person is overweight.


This a great scale that will not only calculate your BMI, but also give you an estimate of your body fat percentage:



Calculate your body fat percentage in a quick and handheld way: