The Body Mass Index (BMI) is a statistical measurement which compares an individual’s weight and height and measures the percentage of body fat. It is the most widely used tool to identify the weight problem. BMI is very easy to measure and evaluate. With the help of BMI one can come to know whether one is underweight, normal weight, overweight or in the category 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 or gain his body weight. Its value is measured in kg/m^{2}.

**How to calculate BMI**

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

Body Mass Index (BMI) = [Body weight/Height x Height]

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

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

Height=1.60 m

Body Weight=70kg

BMI=[70/1.60 X 1.60]=70/2.56=27.34kg/m^{2}

Now with the help of World Health Organisation (WHO) criteria for underweight and obesity, a person may know whether he is under the category of normal weight , underweight, overweight or in the category of obesity.

The categories and BMI

Category |
BMI |

Underweight | <18.5 |

Normal Weight | 18.5-24.9 |

Overweight | 25.0-29.9 |

Obesity Class I | 30.0-34.9 |

Obesity Class II | 35.0-39.9 |

Obesity Class III | >40.0 |

Now after having a glance at the above table it can be said that BMI of the individual, which was 27.34 kg/m^{2 }, falls in the category of overweight which is more than the required or healthy weight.

**Precautions during Measurements:**

- The body weight must be taken on reliable and perfect weighing maschine.
- While taking body weight one must wear minimum required clothes
- One should be bare-footed and his/her body should be in straight position While measuring height.
- Most of the Height measurement tools tells you the height in cm so don’t forget to convert it into m
^{2}