Calculation Of Body Mass Index (BMI)

The Body Mass Index is also known as Quetelet Index because it was invented by Adolphe Quetelet. In fact, it is a statistical measurement which compares an individual's weight and height. Although, it does not actually measure the percentage of body fat yet it is very useful tool to estimate a healthy body weight based on how tall an individual is. Indeed, it is the most widely used tool to identify the weight problem. BMI is very ease to measure and evaluate. With the help of BMI one can come to know whether one is underweight, normal weight, overweight or in the categories of obesity. BMI can be defined as the individual's body weight divided by the square of his height. BMI can be determined by using a BMI chart. BMI helps the person to know whether he is at a healthy weight or need to lose his body weight or gain a weight. Its value is measured in kg/m².

Calculation of BMI

BMI of any individual can be calculated with the help of following formula: 

Body Mass Index (BMI) = Body weight ÷ Height × Height

Here the weight of the individual is measured in kilograms and the height of the individual is taken in meters. 

For example. Suppose that an individual's body weight is 70 kg and his/her height is 1.60 m. Now these values are computed in the formula. 

Height= 1.60 m

Body weight= 70 kg

BMI = 70/1.60 × 1.60 

        = 70/2.56

        = 27.34 kg/m²

Now with the help of world Health Organization (WHO) criteria for underweight and obesity an individual may come to know whether he is under the category of underweight, normal weight, overweight or in the categories of obesity. 

The categories and BMI are given in following table:

Now after having a glance at the above table it can be said that BMI of the individual, which was 27.34 kg/m², falls in the category of overweight which is more than the required or healthy weight. 

The BMI can be simply calculated with the help of Body Mass Index chart which is as follows: 

Precautions during measurements

The following precautions must be taken while taking measurements of height and body weight for calculating BMI: 

1. The body weight must be taken on a reliable and perfect weighing machine. 

2. While taking body weight one must wear minimum required clothes. 

3. While measuring height one should be barefoot and his/her body should be in straight position.