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Baby growth percentile chart
What do baby growth percentiles mean?
A growth percentile places a measurement among healthy children on the WHO growth standards: a baby at the 25th percentile for weight is heavier than about 25 in 100 thriving babies of the same age and sex, and lighter than the other 75. Every line on the chart describes healthy children — half sit below the median and half above by definition. Health professionals read the pattern across visits rather than any single point, plotted in your baby’s own health record at their routine checks.
Look up the WHO range for an age
WHO weight-for-age, girls, 3 months
5.8 kg at the median
About 95 in 100 children on the WHO standard sit between 4.5 kg and 7.5 kg at this age — roughly the 2nd to 98th percentile.
Length: median 59.8 cm, with the same span running 55.6–64.0 cm.
This chart reports the WHO reference — it does not read your baby against it. Half of thriving babies sit below the median and half above, and single points mean far less than the pattern over time. Growth is plotted and read at your baby's health checks, in their own health record, by people who can see the whole picture.
WHO weight reference by age
Weight-for-age from the WHO Child Growth Standards, rounded to 0.1 kg. The span runs from −2 SD to +2 SD — roughly the 2nd to the 98th percentile, covering about 95 in 100 children on the standard.
| Age | Girls — span (median) | Boys — span (median) |
|---|---|---|
| Birth | 2.4–4.2 kg (3.2) | 2.5–4.4 kg (3.3) |
| 1 month | 3.2–5.5 kg (4.2) | 3.4–5.8 kg (4.5) |
| 2 months | 3.9–6.6 kg (5.1) | 4.3–7.1 kg (5.6) |
| 3 months | 4.5–7.5 kg (5.8) | 5.0–8.0 kg (6.4) |
| 4 months | 5.0–8.2 kg (6.4) | 5.6–8.7 kg (7.0) |
| 6 months | 5.7–9.3 kg (7.3) | 6.4–9.8 kg (7.9) |
| 9 months | 6.5–10.5 kg (8.2) | 7.1–11.0 kg (8.9) |
| 12 months | 7.0–11.5 kg (8.9) | 7.7–12.0 kg (9.6) |
| 18 months | 8.1–13.2 kg (10.2) | 8.8–13.7 kg (10.9) |
| 24 months | 9.0–14.8 kg (11.5) | 9.7–15.3 kg (12.2) |
What a percentile is actually saying
A percentile is a position among healthy children, nothing more. The WHO standards followed thriving children and drew the curves through their measurements — so every line on the chart, from the 3rd to the 97th, describes children who are doing well. Half of all thriving babies sit below the median, by definition, and a baby tracking along the 10th percentile is growing exactly as expected for a baby on the 10th percentile.
Why this page shows the reference instead of grading your baby
A single measurement carries almost none of what makes growth interpretable: the trend across visits, corrected age for a baby born early, how the measurement was taken, what feeding looks like. Numbers plotted without that context reassure or alarm at random. The people with the context are the ones who weigh your baby at their routine checks and plot the dot in their health record — which is why growth questions belong at those checks, with the whole curve on the table.
Growth chart questions parents ask
- Is a higher percentile better?
- No. Percentiles describe position among healthy children, not quality — the 15th and the 85th are equally fine places to be. What health professionals look at is whether a child roughly follows their own curve over time, whatever curve that is.
- Why doesn’t this tool calculate my baby’s percentile?
- Because that would be an assessment of your baby, and assessments belong with the people equipped to make them. A percentile calculated from one number, without the growth history, the corrected age, the feeding context or the measurement technique, reads as an answer while carrying none of the information that makes the real answer meaningful. Your child health nurse plots growth in your baby’s health record across visits — that curve is the actual tool.
- My baby’s percentile changed between checks. Is that a problem?
- Percentile movement is common and often unremarkable — measurement conditions vary, growth comes in spurts, and babies born large or small often drift towards the middle over the first year or two. The published advice is that trends over multiple visits are what matter, and questions about your own baby’s pattern are for the nurse or GP who can see the whole chart.
- Which growth chart does Australia use?
- Australian child health services generally plot babies from birth to two years on the WHO Child Growth Standards — the charts printed in each state’s baby health record book. The WHO standards describe how healthy children grow under good conditions, based on breastfed children across six countries.
Where these numbers come from
- World Health Organization — Child Growth Standards — Weight-for-age and length-for-age reference values from birth to 24 months.
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Stop doing this maths in your head
BubSync records the weights and lengths your family enters and shows the history to everyone caring for your baby — a tidy record to bring to each health check, where the actual plotting happens.