Growth Weight Percentile Calculator
Weight Percentile Chart (metric) works out Percentile and Z-score (SD score) from Growth reference, Sex and Age. The default figures on this page give percentile of 3.0 %; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Chart: CDC Weight-for-age, birth to 36 months (girls).
- Reference parameters at 6.5 months: L = 0.35216407, M = 7.454854, S = 0.11489384.
- z = ((X/M)^L - 1)/(L*S) = ((5.9543/7.454854)^0.35216407 - 1)/(0.35216407 x 0.11489384) = -1.880794
- Percentile = Phi(z) x 100 = 3%.
Reference percentile curve at this agetable
| percentile | value | unit |
|---|---|---|
| 3 | 5.954 | kg |
| 5 | 6.131 | kg |
| 10 | 6.409 | kg |
| 25 | 6.892 | kg |
| 50 | 7.455 | kg |
| 75 | 8.047 | kg |
| 90 | 8.606 | kg |
| 95 | 8.952 | kg |
| 97 | 9.181 | kg |
Every chart these inputs supporttable
| chart | measure | value | zScore | percentile |
|---|---|---|---|---|
| Weight-for-age, birth to 36 months | weight-for-age | 5.954 | -1.8808 | 3 |
Figures from CDC and WHO growth charts, checked 31 August 2026. Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed · how reference data is kept current
Sources and references
6 sources
What the Weight Percentile Chart (metric) calculates
Computes a child's growth percentile and z-score for height, weight, BMI, head circumference or weight-for-length against the CDC 2000 growth charts or the WHO child growth standards.
How to use this Weight Percentile Chart (metric)
Enter Growth reference, Sex, Age and Age unit. Percentile updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Percentile, Z-score (SD score) and Reference median for age.
The method follows CDC 2000 Growth Charts - percentile data files with LMS parameters, Kuczmarski RJ et al., 2000 CDC growth charts for the United States: methods and development. Vital Health Stat 11(246), WHO Child Growth Standards - expanded z-score tables (0-5 years), Cole TJ, Green PJ. Smoothing reference centile curves: the LMS method and penalized likelihood. Stat Med 1992;11:1305-19 and CDC, Growth Chart Training: using the WHO growth standards for children under 2 years.
What you can compare
Change one input at a time to see how it affects Percentile, Z-score (SD score) and Reference median for age. The inputs you can vary are Growth reference, Sex, Age, Age unit, Height or length and Weight.
Understanding Percentile, Z-score (SD score) and Reference median for age
A growth percentile is a screening number, not a diagnosis. Serial measurements plotted over time, taken with calibrated equipment, are what a clinician interprets. Discuss any concern with your paediatric provider.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How can I calculate the height and weight percentile for my child?
Computes a child's growth percentile and z-score for height, weight, BMI, head circumference or weight-for-length against the CDC 2000 growth charts or the WHO child growth standards. Open “How this is worked out” beside the result to see each step for your own figures.
How do I calculate my height percentile?
It needs Growth reference, Sex, Age, Age unit, Height or length and Weight. Nothing else is required, and the figures stay in your browser.
What is the correct weight for my height and age?
On the figures this page opens with — age 6.5 and weight 5.9543 — the percentile is 3%. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
How do I calculate my weight percentile?
The result gives Percentile, Z-score (SD score), Reference median for age, Percent of median, Chart used and Reference, each labelled with its unit so the figure can be read on its own.
What is the normal percentile for height and weight?
The page opens with worked default figures: percentile of 3.0 %. Replace them with your own and every figure updates as you type.
What information do I need for the Weight Percentile Chart (metric)?
You need Growth reference, Sex, Age, Age unit, Height or length and Weight. The page opens with default figures that give percentile of 3.0 %, so you can see the scale before entering your own.