# Where’s my child on the growth chart?

Finds a child’s weight and height percentiles from birth to 20, on the WHO standards under 2 and the CDC growth charts from 2.

- Page: https://www.acalculator.org/health/growth-chart-calculator
- JSON spec: https://www.acalculator.org/health/growth-chart-calculator.json
- Version: 5ad26a0e2354

## Default answer

Example with the default inputs (Sex Boy, Based on Age, Years 4, Months 0, Weight 35 lb, Height 40.5 in) on the example date Wednesday, September 30, 2026: At 4 years, weight is at percentile 42.6 and height at percentile 56.1 on the CDC growth charts (2 to 20 years).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| sex | Sex | The child’s sex. Boys and girls have separate growth charts. |
| from | Based on | Enter the age in years and months, or the birth date and the date of the measurement. |
| years | Years | The age in whole years. |
| months | Months | Months past the whole years, 0 to under 12. Decimals are allowed: 2 weeks is about 0.5. |
| born | Birth date | The child’s date of birth. |
| on | Measured on | The date of the measurement. Today, unless you change it. |
| weight | Weight | The child’s weight. |
| height | Height | Height without shoes; under 2, length lying down. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| weightPct | Weight percentile | The share of children of the same sex and age with a lower weight (0.1 to 99.9). |
| weightZ | Weight z-score | Standard deviations of the weight from the median for the age. |
| heightPct | Height percentile | The share of children of the same sex and age with a lower height (0.1 to 99.9). |
| heightZ | Height z-score | Standard deviations of the height from the median for the age. |
| bmi | BMI | Weight ÷ height², when both are entered. |
| age | Age | The age in years and months. |
| chart | Growth charts | The charts used for this age. |

## Method

z = ((x ÷ M)^L − 1) ÷ (L × S); percentile = Φ(z) × 100, with WHO tables under 24 months and CDC from 24.

## Assumptions

- WHO 2006 standards under 24 months (length lying down); CDC 2000 charts from 24 months to 20 years (height standing).
- L, M and S are read on a straight line between table ages; percentiles are rounded half up to 0.1.
- A percentile is not a diagnosis; a doctor looks at growth over time.

## Worked examples

1. sex = female, from = age, years = 5, months = 0.5, weight = 19.950483, height = 1.079566 gives weightPct = 75, weightZ = 0.67449, heightPct = 50, heightZ = 0, bmi = 17.1. Source: CDC wtage.csv P75 and statage.csv P50, girls, 60.5 months.
2. sex = male, from = age, years = 1, months = 3, weight = 11, height = 0.8 gives weightPct = 72.2, weightZ = 0.588625, heightPct = 63.2, heightZ = 0.33759, bmi = 17.2, chart = WHO growth standards (birth to 24 months). Source: WHO boys, month 15.
3. sex = male, from = age, years = 16, months = 0, weight = 60, height = 1.75 gives weightPct = 46.5, heightPct = 57.9, bmi = 19.6. Source: CDC boys, 192 months.
4. sex = male, from = age, years = 3, months = 0, weight = 14 gives weightPct = 41.7, weightZ = -0.210324. Source: CDC wtage.csv, boys, 36 months (between the 35.5 and 36.5 rows).

## FAQ

### How do I read my child’s growth chart percentile?

A percentile is the share of children of the same sex and age in the reference group who measure less. A child at the 60th percentile for height is taller than 60 of every 100 children of that age on the chart.

### Which growth charts does this calculator use?

The ones the CDC advises for US children: the WHO growth standards from birth to 24 months, and the CDC growth charts from 2 to 20 years. The page tells you which chart it used for the age you entered.

### Is it a problem if weight and height are on different percentiles?

Not by itself. Children have different builds. Doctors watch whether each measurement follows its own curve over time, and from age 2 they use BMI-for-age to relate weight to height. The BMI calculator for kids gives the BMI-for-age percentile and category.

### What if my child crosses percentile lines?

Small moves are common, especially in the first two years and around puberty. A steady move across two or more major percentile lines is worth raising with your child’s doctor, who can look at the whole growth record.

### Where is head circumference?

Head size is charted from birth to 24 months on the WHO standard. Use the baby percentile calculator for a baby’s weight, length and head circumference together.

### Can I enter just one measurement?

Yes. Leave the other empty. The calculator needs a weight or a height.

## Sources

- Centers for Disease Control and Prevention, National Center for Health Statistics. CDC growth charts data files: weight-for-age and stature-for-age, 2 to 20 years (wtage.csv, statage.csv), with the LMS instructions. https://www.cdc.gov/growthcharts/cdc-data-files.htm
- Centers for Disease Control and Prevention. WHO growth charts data files: weight-for-age and length-for-age, birth to 24 months (CDC copies of the WHO tables). https://www.cdc.gov/growthcharts/who-data-files.htm
- WHO Multicentre Growth Reference Study Group. WHO Child Growth Standards: length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age. Methods and development. Geneva: World Health Organization, 2006. https://www.who.int/publications/i/item/924154693X
- Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital Health Stat 11. 2002;(246):1-190. https://www.cdc.gov/nchs/data/series/sr_11/sr11_246.pdf
- Grummer-Strawn LM, Reinold C, Krebs NF. Use of World Health Organization and CDC growth charts for children aged 0-59 months in the United States. MMWR Recomm Rep. 2010;59(RR-9):1-15. https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5909a1.htm
- Marsaglia G. Evaluating the normal distribution. J Stat Softw. 2004;11(4):1-11 (the series used for Φ). https://doi.org/10.18637/jss.v011.i04