Guide to Understanding Growth Charts for Children

Growth Charts

Kids growth charted on a door frame.
How do you keep track of how well your kids are growing?. Photo by Cultura RM/Ian Nolan

Growth charts help pediatricians figure out if children are growing and gaining weight well.

After measuring your child's height, weight and head circumference at each routine well child check up, your pediatrician will plot them on a growth chart to see if your child is growing normally.

Growth charts can also make it easy for parents to follow their children's growth.

Although parents typically focus on whether a child is at the top or bottom of the growth charts, your pediatrician will likely be more interested that:

  • your child is following his or her growth curve
  • your child is not crossing percentiles

But remember that instead of just one point in time, the information about how your child is growing over time is what's important on a growth chart.

And while we used to have just one set of growth chart for children, the 1977 growth charts that were developed by the National Center for Health Statistics, there are now CDC growth charts that were updated and revised by the CDC in 2000, growth charts from the World Health Organization (WHO) that reflect an international standard (2006),  and growth charts that focus only on WIC aged children (2012).

There are also growth charts for premature babies and children who are born with specific conditions, such as Down syndrome, Prader-Willi syndrome, Achondroplasia, and Marfan syndrome, etc.

The Magic Foundation offers specialized growth charts for children with Noonan syndrome, Turner syndrome, Russell-Silver syndrome, etc.

In general, you should use the WIC growth charts up until age 2 years and then use the CDC growth charts.

Understanding Growth Charts

Plotting a a child's growth on the 75th percentile.
Learn how to plot your child's percentile on a growth chart. Photo by Vincent Iannelli, MD

Since  growth charts compact a lot of information into a small space, they can be a little confusing to use.

Learning to plot your child's growth is fairly easy once you get the hang of it though - almost as easy as learning your A, B, C's...

First (after you get your child's growth chart),  find your child's age at the bottom of the chart (step A on the chart above) and draw a vertical line (a straight line up and down) on the growth chart. In our example, we drew a line through 24 months or 2 years.

Now find your child's weight on the right hand side of the chart, 30 pounds in our example, and draw a horizontal line (a straight line from side to side). This is step B in our example. Keep in mind that you don't have to really physically draw a line on the growth charts. If you really do that each time, your growth chart will look very messy and will be hard to read. Instead, just imagine where the line should be or draw a light line with a pencil that you can later erase.

Step C involves finding the spot where these two lines intersect or cross each other. Find the curve that is closest to this spot and follow it up and to the right until you find the number that corresponds to your child's percentile (step D).

In our example, you can see that a two year old boy who is 30 pounds is at the 75th percentile for his weight. What does that mean? It means that he weighs more than about 75% of boys his age. It also means that 25% of 2 year old boys weigh more than he does. Is that normal? Sure, if that is where he has always been on the growth charts.

Finding your child's percentile is a little harder if a curve doesn't actually pass through the spot where your child's age and weight come together. For example, what would you do if the boy in our example actually weighed 31 pounds? You would use all of the same steps and would have to imagine a curve that is somewhere between the 75th and 90th percentiles and figure that he was at about the 80th-85th percentile.

If your child is above the 95th or below the 5th percentile, then you will also not be able to find an exact percentile, except to say that he is above or below the growth chart.

You can use the same steps to plot your child's height and body mass index.

Here are some more examples (try them before looking at the answers below):

  1. What is the percentile for a 2 year old boy who is 2 feet 10 1/2 inches (34 1/2 inches)?
  2. What is the percentile for a 13 year old girl who is 80 pounds?
  3. What is the percentile for a 16 year old girl who is 5 foot 4 inches (64 inches)?
  4. What is the percentile for a 9 year old who has a body mass index of 18?
  5. What is the percentile for a 6 month old girl who is 14 pounds?

It is also important to understand that the growth charts are best used to follow your child's growth over time or to find a pattern of his growth. Plotting your child's weight and height at different ages and seeing if he follows a growth curve is more important than where he is at any one time. Even if your child is at the 5th percentile for his weight, which means that 95% of kids his age weigh more than he does, if he has always been at the 5th percentile, then he is likely growing normally. It would be concerning and it might mean there was a problem with his growth if he had previously been at the 50th or 75th percentile and had now fallen down to the 5th percentile.

Also remember that children between the ages of 6 and 18 months can normally move up or down on their percentiles, but older children should follow their growth curve fairly closely.

Answers to examples: A) 50th percentile, B) 10th percentile, C) 50th percentile, D) 75th percentile, E) about the 15th percentile

Growth Charts for Infants and Toddlers

How well is your child growing?
Your baby will be measured at each check up so that her growth can be plotted on a growth chart. Photo by Vincent Iannelli, MD

That there are multiple sets of growth charts available for newborns, infants, and toddlers is likely to confuse many parents.

Just remember that the CDC advises that parents use the WHO growth charts until age two years:

The CDC growth charts can be used for older toddlers, although they are available for infants too:

These are standard growth charts that include the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentiles. If you prefer, the CDC also has growth charts that start with the 5th percentile.

Growth Charts for Older Children and Teens

A pediatrician measures a child's height.
Your child's height should be measured at each check up so that it can be plotted on a growth chart. Photo by BJI / Blue Jean Images

Need to plot your older child's weight, height (stature), or body mass index?

Older children, including preschoolers, school age children, and teens, should use the CDC growth charts:

These are standard growth charts that include the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentiles. If you prefer, the CDC also has growth charts that start with the 5th percentile.

WHO growth charts are also available for older children:

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