Baby growth chart (0–24 months)
A baby growth chart is a set of percentile curves showing how children of the same age and sex distribute across a measurement — weight, length, or head circumference. For babies under 24 months the chart almost always uses the WHO Child Growth Standards (2006), based on ~8,400 healthy infants raised under optimal conditions in six countries.
Want your baby's percentile right now? Use the baby percentile calculator — it plots your measurement on the same WHO chart and shows the percentile instantly.
What the lines mean
Each curve is a percentile — 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th. If your baby lands on the 50th, half of healthy babies of the same age and sex weigh (or measure) less, and half more. The 50th isn't a target — most babies aren't on it. Anywhere between the 3rd and 97th is considered normal for a healthy infant.
Weight-for-age vs length-for-age
WHO publishes separate charts for each measurement. Weight-for-age answers "how heavy is my baby compared to others her age?" Length-for-age answers the same question for length. The two often don't match — a baby can be 20th percentile for weight and 60th for length, which just means she's relatively long-and-lean. That's shape, not a problem.
Length, not height
Under 24 months, babies are measured lying down (recumbent length) rather than standing up. Standing height is typically 0.5–1 cm shorter than recumbent length on the same child, and the WHO charts assume length. Don't mix the two, or the percentile will read low.
Percentile crossing in the first year
Babies frequently cross percentile lines in the first 12–18 months as they "canalize" onto their genetic trajectory — often downward from birth weight (which is strongly influenced by pregnancy) toward their long-term curve. Pediatricians generally pay attention when a baby crosses two or more major percentile bands sustained across several visits. A single low or high reading is almost never meaningful in isolation.
WHO chart ages 0–24 months, CDC from 24 months on
WHO's infant charts stop at 60 months, but in practice most US clinics follow WHO strictly only through 24 months, then switch to the CDC 2000 charts for the rest of childhood. If your baby is over 24 months, start from the toddler growth chart.