Growth charts
Child growth charts, decoded
Pediatricians have used growth charts for decades because one measurement says little — but a pattern says a lot. Here is how to read the curves like a pro.
A child growth chart plots height against age on reference percentile curves (P3–P97). What matters most is growing steadily along a channel over time — GrowTall plots your child's measurements on WHO and CDC curves automatically.
What the curves mean
A growth chart shows height-for-age with several curved lines labeled P3, P15, P50, P85 and P97 (sometimes P5–P95). Each line marks where a percentile of children sits at a given age. The 50th percentile (P50) is the median — half of children measure above it, half below.
A child at the 33rd percentile is taller than about 33 of 100 peers. That is a normal location, not a grade. See our plain-language guide to height percentiles.
WHO vs. CDC — which chart, when
| Chart | Ages | Basis | Use it for |
|---|---|---|---|
| WHO Standards | Birth – under 2 | Optimal conditions, six-country study | Infant length-for-age |
| CDC 2000 | 2 – 20 | US national reference survey data | Standing height-for-age, BMI-for-age |
GrowTall switches automatically: WHO curves while a profile is under two, CDC curves from age two. Details in our WHO chart and CDC chart guides.
Reading the chart in GrowTall
GrowTall draws the P3–P97 percentile corridor and plots your child's measurements on top as a connected path. A tooltip shows the latest height and percentile, and tabs switch between the height curve, the percentile view and growth velocity in cm/year.
The healthy signal is steady growth along a channel — a child cruising near P25 for years is usually doing exactly what their genes intended.
Patterns worth discussing
Growth charts are screening tools, not diagnoses. Pediatric guidance generally suggests a closer look when:
- A child crosses two or more major percentile channels downward (or upward) over 6–12 months.
- Growth velocity falls below roughly 4 cm/year during mid-childhood (about ages 4 to puberty).
- Height tracks far from the mid-parental target range without explanation.
Any of these is a reason for a conversation with a pediatrician — and GrowTall's consultation summary is designed to make that conversation easier.
Common questions
Which growth chart does GrowTall use for a 3-year-old?
CDC 2000 height-for-age, which applies from ages 2 to 20. WHO Child Growth Standards are used from birth to age 2, while length is measured recumbent.
Is a low percentile bad?
Not by itself. Percentiles describe where a child sits in a reference population. Many healthy children live their whole childhood at the 10th or 90th percentile. The trend over time matters more than the position.
How often should we update the chart?
Every 60–90 days is ideal. More frequent measurements mostly capture normal daily height variation rather than true growth.
See the bigger picture of growth.
Track every measurement, understand the trend and keep a reliable growth record — free to start, no ads.