How to Calculate Pediatric BMI

Calculating your child's body mass index may be a better indicator of whether he is in the correct weight range than simply using his weight alone. BMI measurements also take height into account, making the result a more complete picture of where your child falls in regards to his weight. The Centers for Disease Control finds that BMI calculations are the best way to screen for obesity in children. However, it is important to note that while a high BMI may be indicative of obesity, it is not automatically a diagnosis. If your child's BMI falls in the range of obesity, further test and examination by your pediatrician is required.

Things You'll Need

• Weight scale
• Paper
• Pen
• Measuring tape
• Calculator

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Instructions

• 1

  Weigh your child on the scale, writing the results on the paper.

• 2

  Measure your child's height using the measuring tape. Note the results on the paper.

• 3

  Using the calculator, multiply the height measurement in inches, by itself, essentially squaring the figure. Note the resulting figure on the paper. For example, if your child is 4 feet, 2 inches tall, you multiply her height in inches, 50, by itself: 50x50=2,500.

• 4

  Divide the weight measurement, in pounds, by the height squared figure. Jot down your result. So, if your child weighs 75 lbs at the height of 4 feet, 2 inches, you divide 75 by 2,500, equaling .03.

• 5

  Multiply the figure gained from dividing the weight by the height squared by 703. Continuing with the example, you multiply .03 by 703 to equal 21.1.

• 6

  Write down this final figure. This is your child's BMI. Your child, at 4 feet, 2 inches and weighing 75 pounds, has a body mass index of 21.1.