How to Calculate BMI for Boys

A considerable number of children in the United States are overweight due to unhealthy eating habits and lack of exercise. For many kids, video games, computer activities and television take the place of running and playing. Excess weight can increase the chance of health problems during childhood and later in life. Body mass index (BMI) is a measurement of body fat, and it can provide a healthy weight range for a child. In order to figure a boy's BMI, perform a few calculations and use a percentile chart for comparisons.

Instructions

Figuring a Boy's BMI

• 1

  Measure the boy's height and weight.

• 2

  Square the boy's height in inches. If the boy stands 60 inches tall, the squared figure would be 3,600.

• 3

  Multiply the boy's weight by 703. If the total is 110 pounds, the figure would be 77,330.

• 4

  Divide the answer from step 3 by the answer from step 2. Therefore, 77,330 divided by 360 equals 21.48. The boy's BMI is 21.48.

• 5

  Compare this figure to the percentiles on the BMI chart, based on the boy's age. Consult the horizontal axis for the age, the vertical axis for the BMI measurement. The point at which these two lines intersect provides the percentile that the boy falls into. In this example, assume that the boy is 14 years old. This would place him around the 30th percentile, according to the chart. (See Resources.)

• 6

  If the boy is in the fifth percentile or below, he is considered underweight. A normal weight range is between the sixth percentile and the 84th percentile. A boy is considered overweight if his BMI falls between the 85th percentile and the 94th percentile. Obesity is located above the 94th percentile.