Baby Growth Percentile
See where your baby's weight and length fall on the WHO Child Growth Standards curve for ages 0–24 months.
Based on WHO Child Growth Standards (0–24 months). Percentiles are estimates — your pediatrician's measurements take priority.
How to read percentiles
A percentile tells you what fraction of babies the same age and sex are smaller than yours. The 50th percentile is the median: half are below, half above. Both the 5th and the 95th percentiles include perfectly healthy babies — the curve simply describes the natural range of human variation.
Trajectory beats single numbers
What pediatricians watch most closely is whether your baby stays roughly on their own curve over time. A baby who has been at the 30th percentile for six months and is still at the 30th percentile is growing well. A baby who drops from the 70th to the 30th in a month is worth a closer look.
WHO vs. CDC standards
For babies 0-24 months, the CDC recommends WHO Child Growth Standards — they are based on a multinational sample of breastfed babies raised in optimal conditions, representing how children should grow under good care. After age 2, CDC charts are typically used.
When to ask your pediatrician
- Sudden change of more than two major percentile lines (e.g. 50th to 10th)
- Falling below the 3rd or above the 97th percentile
- Plateau or weight loss between visits
- Length and weight diverging significantly (large head, very thin body, etc.)
Your provider has access to multiple visits' worth of data and the full clinical picture — trust them over any online calculator, including this one.
Frequently asked questions
What does "50th percentile" mean?
The 50th percentile is the median — half of babies the same age and sex are smaller, half are larger. It is not the "ideal" or "target." Healthy babies span the full curve.
Should I worry about a low (or high) percentile?
A single percentile rarely matters as much as the trajectory. If your baby was steadily at the 25th percentile and stays there, that's their healthy curve. A sudden drop or jump is what providers watch for.
WHO vs. CDC growth charts?
The CDC recommends WHO standards for ages 0–24 months because they are based on breastfed babies in optimal conditions. From age 2 on, CDC charts are typically used. We use WHO data here.
Why does this only go to 24 months?
WHO standards for 0–24 months are the most consistent reference globally. After 2 years old, growth patterns vary more by environment and nutrition, so providers use different growth charts.
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