Measuring

• 1). Position your child with his or her back to a wall. Make sure your child is standing flat-footed with erect posture and looking straight ahead.
  
  
• 2). Mark the wall at a level that is equal to the top portion of your child's head.
  
  
• 3). Measure from the floor to the mark with a tape measure to determine your child's height. Record this measurement.
  
  
• 4). Instruct your child to remove shoes or heavy articles of clothing, then have him or her stand on a scale. Record this measurement.
  
  

Finding Percentile

• 1). Obtain a growth percentile chart from your doctor, or go to a website that provides standardized growth charts, such as the Centers for Disease Control and Prevention. If you find a chart online, click on the chart that applies to your child's age and gender.
  
  
• 2). Locate your child's age along the top or bottom horizontal axis of the chart. Place your finger or a pencil on this position.
  
  
• 3). Move your finger or the pencil downward or upward (depending on whether you are starting from the top or bottom of the chart) until you reach your child's length (height) and weight measurements on the vertical axis. The point at which the age and measurements intersect is your child's percentile. Look to the right side of the chart to see the number that corresponds with the percentile. For instance, if your child's height corresponds with a line that has a 50 on it, it means that your child is in the 50th percentile for height, which is exactly average.