## Calculating BMI

Calculating BMI is a mathematical process of categorizing your weight according to your height. The calculation can be made manually or via an automated method. BMI categories are underweight, normal weight, overweight and obese.

The calculation is made by dividing your weight in kilograms by your height in meters squared. The equation is as follows:

BMI = Weight (in kilograms) ÷ Height (in meters) 2

Since weight and height measurements are more commonly made in pounds and inches respectively, if the BMI calculation is made manually, it is much more practical to divide the weight in pounds by the height in square inches and multiply by a conversion factor which changes kilograms per square meter into pounds per square inch. That conversion factor is 703.1. Therefore, the new equation for calculating BMI using the weight and height recorded in pounds and inches rather than kilograms and meters is as follows:

BMI = Weight (in pounds__)__ X 703.1 ÷ Height (in inches) 2

Calculating BMI is rarely done manually however, because of the various electronic devices Age calculator that are currently available. Some BMI, calculators are handheld while others are computer-based. A hand-held BMI calculator might be an app on a mobile device or a standalone device. Some computer-based calculators require an Internet connection for BMI calculation, whereas others can be installed on computers as independently operating programs.

Calculating BMI with any of the electronic devices consists of entering weight and height in the respective fields, then clicking the appropriate button to perform the BMI calculation. Weight unit might be in pounds or kilograms and the height unit might be in inches, feet and inches, or centimeters, depending on the calculator.

A BMI calculator for men is no different from that used to calculate BMI for women, but a BMI calculator for children is a little different inasmuch as there is a field for entering age in addition to the fields for the weight and height. The age field takes into account the fact that children are still growing and that their growth rate varies with age. By factoring in age, the BMI calculation for child is then compared with that of other children of the same age, and is expressed as a percentile, which is a more precise weight-category indicator. For example, a child with a BMI calculation in the 50 percentile means that 50% of children of the same age weigh more and 50% of children of that same age weigh less than the child whose BMI was calculated. On the other hand, a child with a calculated BMI in the 95 percentile weighs more than 95% of children of the same age and weighs less than only 5% of children of the same age.