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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.
Plot a measurement on the chart
The published curves your baby's health checks plot against — and, if you enter one, your own measurement drawn on them with the percentile it works out to.
WHO Child Growth Standards — weight (kg) for girls. Birth to 24 months, by age. The solid line is the 50th percentile; the dashed lines are the 3rd, 10th, 25th, 75th, 90th and 97th.
Counted from the birthday. The chart covers birth to 24 months.
In kilograms, as the standard publishes it.
Enter an age and a weight to plot it on the chart.
This is a charting tool: it works out where a measurement sits on the published curves and draws it, and it stops there. It does not say whether that position is expected for your baby, and nothing here changes with the answer. Every line on the chart, from the 3rd to the 97th, was drawn through children who were growing well, and half of all thriving babies sit below the median by definition — what a percentile means for one particular baby depends on their history, their birth, their feeding and their own pattern over time, which is read at their health checks by people who can see all of it.
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 lookup reports the published WHO row for an age — it does not read your baby against it; plotting a measurement is what the chart above does. 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 an Australian growth percentile page, and who is behind it
Search for a growth percentile calculator in Australia and the first results belong to infant formula marketers. That is not an accusation, it is a disclosure worth reading before you trust a chart: a page whose publisher sells formula has a reason to want a parent worried about weight. This page is published by BubSync, which is owned by the family that built it and takes no money from formula, pharmaceutical or employer-benefits companies. It plots the WHO Child Growth Standards, the same charts printed in each Australian state's baby health record book, and the INTERGROWTH-21st preterm standards before the due date, and it says nothing about what a position means, because that is the child health nurse's job.
What this tool does, and where it stops
Plotting a measurement is arithmetic on a published table, and it is the same arithmetic whoever does it — the tool shows its working so you can check it. Reading the result is a different job. A single dot 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. So nothing here interprets the number it gives you — there is no threshold in this page, no wording that changes with the answer, and the same sentences appear whether a measurement lands on the 3rd percentile or the 97th. 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 where growth questions belong, 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.
- What does this tool do with the measurement I enter, and what does it not do?
- It charts it. It finds the published curves for that age and sex, works out where the measurement falls on them, draws the dot and reports the percentile — and it shows the arithmetic, so the number is checkable rather than something to take on trust. What it will not do is tell you what that position means for your baby, because a single measurement carries none of the things that make growth interpretable: the trend across visits, the corrected age for a baby born early, how the measurement was taken, what feeding looks like. Your child health nurse plots growth in your baby’s health record across visits, and reads it with all of that in view.
- 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.
- Is this a growth percentile calculator for Australia?
- Yes, in the sense that matters: it plots on the WHO Child Growth Standards that Australian child health services use from birth to two years, the charts printed in the blue book in New South Wales, the red book in Queensland and their equivalents in every state, and on the INTERGROWTH-21st preterm standards before the due date. It is published by an Australian company with no formula or pharmaceutical money behind it, and it does not interpret a result.
- 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.
- My baby was born early — is the WHO chart the right one?
- Babies born preterm are usually plotted on a preterm standard first. The INTERGROWTH-21st preterm postnatal standards run by post-menstrual age — weeks counted from the start of the pregnancy rather than from the birth — so a baby born at 30 weeks is compared with other babies at the same stage of development instead of with newborns. Switch the chart above to “Born preterm” to see those curves, with the due date marked at 40 weeks. Which chart your own baby is plotted on, and when they move across, is decided by the team caring for them.
- What is corrected age, and does it change the chart?
- Corrected age is a preterm baby’s age counted from their due date rather than their birthday — a baby born ten weeks early is four weeks corrected at fourteen weeks old. Once a preterm baby is being plotted on the WHO charts, health professionals generally plot them at their corrected age, which is why the same baby can look very different on the two charts. The published curves themselves do not change; which age you read them at does.
Where these numbers come from
- World Health Organization — Child Growth Standards — Weight, length and head-circumference reference values from birth to 24 months, with the LMS parameters the percentile arithmetic uses.
- INTERGROWTH-21st — Preterm Postnatal Growth Standards — Weight, length and head circumference curves for babies born preterm, by post-menstrual age from 27 weeks (Villar J, et al. Lancet Glob Health 2015;3(11):e681-91).
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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.
