Body Mass index


A calculation used to determine one’s amount of body stout is called Body mass index (BMI). It is also known as Quetelet Index. More than a hundred years ago, a Belgian mathematician and scientist named Lambert Adolphe Quetelet developed the formula used to calculate BMI.  The formula for BMI calculation was not usually used in the United States but interests increased in the early 1980’s when researchers observed that most Americans have rapidly increasing weights.

Today, this is one of the considerations used in determining health risks due to being underweight, overweight or obese. Note that BMI is a comparative index. It does not measure the amount of body stout directly.

Body Mass index calculator

Weight and Height measurements are the requirements for calculating BMI. In calculating BMI using the following:

ü  metric units

  • weight measured in kilograms(kg) is divided by the height squared which is measured in meters (m)

ü  imperial units

  • weight measured in pounds (lb) is divided by height squared in inches(in) and then multiplied by 703.

The result of this calculation is then compared to the statistical distribution of BMIs for adults ages 20 – 29. With this, one will know whether he or she is underweight, average weight, overweight or obese. The 20-29 age group became the basis of comparison because it represents fully developed adult bodies with statistically least amount of body stout.

For Children, the formula for calculating BMI is the same as that of the adults but the results are interpreted differently.

Body Mass Index Chart

Adults aging 20 and above are evaluated on the same BMI scale below:

BMI below 18.5: Underweight
BMI 18.5-24.9: Normal weight
BMI 25.0-29.9: Overweight
BMI 30 and above: Obese

A BMI of 17 or below is considered to be an indication of malnourishment. In developed countries, having this number without any disease is an indication of anorexia nervosa. A BMI of 40 or above indicates morbid obesity which can place an individual at risk of having obesity-related diseases like heart attack, stroke and type 2 diabetes.

For children, the following are considered in the interpretation of BMI:

  • Amount of body stout changes as children grow
  • The amount of body stout is different in boys and girls with the same age and weight

Below is the weight category for children:

  • Below the 5th percentile: Underweight
  • 5th percentile to less than the 85th percentile: Healthy weight
  • 85th percentile to less than the 95th percentile: At risk of overweight
  • 95th percentile and above: Overweight
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