How to Read a Child Growth Chart

A child growth chart is a picture of a reference, read by age. The lines are heights in the WHO 2007 height-for-age data for ages 5–19. The chart does not, by itself, contain a child’s measurements. Those appear only when someone plots them.

The growth charts on this site draw those reference curves, separately for boys and girls. They are separate from any private record.

What the curves mean

Age runs along the horizontal axis. Height runs up the vertical axis, in centimeters. Each curve is a percentile in the reference: on these charts, the 3rd, 15th, 50th, 85th, and 97th. A curve is a path of heights across age for that place in the spread.

A curve is not a plan for one child, and it is not a line labeled “too short” or “too tall.” Many children and teenagers grow near one curve for a while. Others move gradually relative to the curves. The chart is a backdrop. It does not assign a path, and it does not diagnose.

What a percentile means on the chart

The curves nearest a plotted point show where that height sits in the reference for that age and sex. That place is the height percentile. A point on the middle curve is near the median. A point between curves is still a comparison. It is not a gap that has to be closed, and it is not evidence that a higher curve would be healthier.

How to read one recorded measurement

A single point is one height on one date. Find the age along the bottom, then the height. The height calculator reports the same kind of comparison as a percentile and a z-score, using one published reference row for the completed month of age. It does not interpolate between rows.

Read the point as a comparison, not a score.

Why the pattern over time matters

One point cannot show direction. Two or more measurements, taken the same way and plotted over time, show whether later heights stay in a similar part of the reference. That pattern is the trajectory. Growth velocity is the change between two of those recorded heights. The growth velocity calculator reports that change per year. It describes what was recorded. It is not a forecast of adult height.

A short gap between measurements can look like a jump or a stall when the difference is mostly technique. A longer series is easier to interpret than two points taken a few days apart.

Parents often want a chart to answer whether a recorded pattern is okay. The chart can show where a height sits and how later heights compare with it. It cannot decide that something is wrong. If a pattern worries you, a qualified clinician can look at the child, not just the dots. The guide for parents covers that distinction.

Common questions

Are the curves a target?

No. They describe the WHO reference at each age. They are not the height a child is supposed to reach.

Does this chart already include a child’s measurements?

The reference charts on this site show the curves only. A recorded height is compared with those curves when you enter it. The page itself does not plot a private record.

Can a growth chart diagnose a growth problem?

No. A chart cannot diagnose. Questions about a child’s health belong with a qualified clinician.