Weight
Weight for age, the curve most parents are shown first.
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See where a measurement sits on the real growth curves
You came home from a checkup with a number. This site draws the official WHO and CDC reference curves, puts your number on them, and explains what the number is actually measuring. It does not tell you what it means for your child, because that is your pediatrician's job and not a web page's.
Plot a measurement What a percentile means
Percentiles describe position in a reference population, not health. Growth patterns are for your pediatrician to read.
Quick answer
What is a growth percentile?
A growth percentile is a position in a reference population, not a grade. A weight on the 30th percentile means about 30 children in 100 of the same age and sex in the reference group weigh less, and about 70 weigh more. Every band on the chart is occupied by healthy children, by construction.
What the tool does
Length or height
Measured lying down (length) under 24 months and standing (height) from 24 months, which is also where the reference table changes.
Head circumference
Measured around the widest part of the head. This one stays on the WHO standard the whole way.
- Birth to 60 months. The WHO Child Growth Standards through 24 months, then the CDC 2000 Growth Charts, which is the split US pediatric practice uses. The chart marks the seam rather than smoothing it away.
- Metric or US customary. Enter kilograms and centimetres, or pounds and inches. The maths runs in metric either way and converts at the edges.
- One visit or a whole series. Add a row per measurement and the chart connects them into a trend line. You can enter ages in months, or a date of birth and a date measured.
- Nothing leaves your browser. The reference tables download with the page and every calculation runs on your device. Your entries are never sent anywhere and are not saved between visits.
Where the curves come from
374 published parameter rows, downloaded from the agencies themselves and reproduced exactly. Every percentile on this site is solved from them, never copied from somebody else's compiled table. For instance, the WHO 50th percentile weight for a 12 month old boy works out at 9.65 kg, or 21.3 lb, computed from the row below.
| Reference | Measurement | Rows per sex | Retrieved |
|---|---|---|---|
| WHO | WHO Child Growth Standards (2006), weight-for-age | 25 | 2026-08-28 |
| WHO | WHO Child Growth Standards (2006), length-for-age (recumbent length, 0 to 24 months) | 25 | 2026-08-28 |
| WHO | WHO Child Growth Standards (2007 head circumference release), head-circumference-for-age | 61 | 2026-08-28 |
| CDC | CDC 2000 Growth Charts, weight-for-age (2 to 20 years) | 38 | 2026-08-28 |
| CDC | CDC 2000 Growth Charts, stature-for-age (2 to 20 years) | 38 | 2026-08-28 |
Understand the number before you worry about it
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How to take a measurement at home that is worth plotting
Technique, not interpretation: how weight, length, standing height and head circumference are measured for a growth chart, and where the error creeps in at home.
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What a growth percentile actually means
A percentile is a position in a reference population, not a grade. Here is exactly what the number is measuring, where it comes from, and what it cannot tell you.
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Why the 10th percentile is a completely ordinary place to be
Ten percent of a healthy reference population sits at or below the 10th percentile, by construction. Here is the arithmetic of why the low bands are populated, and what the number does and does not tell you.
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Why the WHO and CDC growth charts differ, and why the switch happens at two
One is a prescriptive standard built from six countries, the other a descriptive US reference. The history explains the shape of both charts and the visible step at 24 months.
What this site will never do
It will not tell you whether a measurement is good, flag anything, screen for anything, or give feeding or development guidance. Not because those questions do not matter, but because answering them takes a clinician who knows your child's history, and a chart that pretended otherwise would be worse than useless.
What it will do is show you the real curves, show you exactly how the number is calculated, and publish the source data so you can check it. For growth and development questions, talk to your pediatrician, and see the CDC growth chart pages for the source material.