Where’s my child on the growth chart?
Enter your child’s sex, age, weight and height to see where they sit on the growth charts, as percentiles and z-scores.
- Weight percentile
- 42.6
At 4 years, weight is at percentile 42.6 and height at percentile 56.1 on the CDC growth charts (2 to 20 years).
- Weight z-score
- -0.19
- Height percentile
- 56.1
- Height z-score
- 0.15
- BMI
- 15
- Age
- 4 years
- Growth charts
- CDC growth charts (2 to 20 years)
Answer for the example date Wednesday, September 30, 2026. It changes to today's date when the page loads.
Weight percentile: 42.6. At 4 years, weight is at percentile 42.6 and height at percentile 56.1 on the CDC growth charts (2 to 20 years).
Where does the weight fall?
Where does the height fall?
This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use
How to calculate
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.
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).
Method: z = ((x ÷ M)^L − 1) ÷ (L × S); percentile = Φ(z) × 100, with WHO tables under 24 months and CDC from 24.
- 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
Each example is checked against the calculator on every build.
- Sex Girl, Based on Age, Years 5, Months 0.5, Weight 43.98 lb, Height 42.5 in gives Weight percentile 75, Weight z-score 0.67449, Height percentile 50, Height z-score 0, BMI 17.1.Source: CDC wtage.csv P75 and statage.csv P50, girls, 60.5 months
- Sex Boy, Based on Age, Years 1, Months 3, Weight 24.25 lb, Height 31.5 in gives Weight percentile 72.2, Weight z-score 0.588625, Height percentile 63.2, Height z-score 0.33759, BMI 17.2, Growth charts WHO growth standards (birth to 24 months).Source: WHO boys, month 15
- Sex Boy, Based on Age, Years 16, Months 0, Weight 132.3 lb, Height 68.9 in gives Weight percentile 46.5, Height percentile 57.9, BMI 19.6.Source: CDC boys, 192 months
- Sex Boy, Based on Age, Years 3, Months 0, Weight 30.86 lb gives Weight percentile 41.7, Weight z-score -0.210324.Source: CDC wtage.csv, boys, 36 months (between the 35.5 and 36.5 rows)
How it works
1. Age in months. Enter the age as years and months (months may have decimals), or as a birth date and a measurement date:
- age in months = 12 × years + months, or
- age in months = (measurement date − birth date, in days) ÷ 30.4375.
No answer if the measurement date is before the birth date, or if the age is over 240 months (20 years).
2. The charts. Under 24 months: the WHO weight-for-age (kg) and length-for-age (cm, lying down) standards, one row per whole month from 0 to 24. From 24 to 240 months: the CDC 2000 weight-for-age (kg) and stature-for-age (cm, standing) charts, with rows at 24 months, then 24.5, 25.5 and so on to 239.5, then 240. All tables are used exactly as published.
3. L, M and S at the age. At a table age the row is used as it is. Between two table ages a₀ < a < a₁, each of L, M and S is read on a straight line: L = L₀ + (a − a₀) ÷ (a₁ − a₀) × (L₁ − L₀), and the same for M and S.
4. Each percentile. For each measurement x entered (weight in kg, height in cm):
- z = ((x ÷ M)^L − 1) ÷ (L × S), or z = ln(x ÷ M) ÷ S if L is 0;
- percentile = Φ(z) × 100, where Φ is the standard normal cumulative distribution.
Each percentile is rounded half up to one decimal place (the decimal value decides) and then kept between 0.1 and 99.9. Each z-score is shown to two decimal places. Weight and height are each optional, but at least one is needed.
5. Other rows. BMI = weight ÷ height² (kg and m), rounded half up to one decimal place, when both are entered. Age: the age in months rounded half up to one decimal place, as years and months. Growth charts: "WHO growth standards (birth to 24 months)" or "CDC growth charts (2 to 20 years)".
The two bars show where each percentile falls between 0 and 100.
Rounding. Every “rounded half up” on this page reads the decimal value: a result within 1e-9 (relative) of a half counts as the half. For example, 80 ÷ 1.6², which a computer stores as 31.249999999999993, rounds to 31.3.
Assumptions
- The CDC advises the WHO standards under 2 years and the CDC charts from 2 to 20. At 24 months, the switch from length lying down to height standing can move the height percentile a little.
- One set of measurements is a snapshot; doctors look at growth over several visits.
- Φ is computed with Marsaglia’s series, which matches the exact value to within 5e-15; percentiles beyond z = ±8 show as 0.1 or 99.9.
- This calculator gives general information. It is not medical advice or a diagnosis; talk to your child’s doctor about their growth.
Worked examples by hand
A girl of 5 years 0.5 months (60.5 months), 19.95048336 kg and 107.9566031 cm. These are the CDC table’s 75th percentile weight and 50th percentile height for girls at 60.5 months. Weight: z = 0.6745, the 75.0 percentile. Height: the height equals M, so z = 0 and the percentile is 50.0. BMI = 19.9505 ÷ 1.0796² = 17.1.
A boy of 1 year 3 months (15 months): 11 kg and 80 cm. The WHO boys’ rows for month 15: weight L = 0.0413, M = 10.3108, S = 0.11007, so z = ((11 ÷ 10.3108)^0.0413 − 1) ÷ (0.0413 × 0.11007) = 0.5886, percentile 72.2; length L = 1, M = 79.1458, S = 0.03197, so z = (80 ÷ 79.1458 − 1) ÷ 0.03197 = 0.3376, percentile 63.2. BMI = 11 ÷ 0.8² = 17.19, shown as 17.2.
A boy of exactly 3 years (36 months), 14 kg, no height. Halfway between the CDC boys’ rows for 35.5 and 36.5 months: L = −0.603195, M = 14.330212, S = 0.111625. z = ((14 ÷ 14.330212)^−0.603195 − 1) ÷ (−0.603195 × 0.111625) = −0.2103, percentile 41.7. With no height, the height rows and BMI are left out, and so is the answer sentence, which names both percentiles.
A boy of 16 years (192 months), 60 kg and 175 cm. 192 months is halfway between the CDC rows for 191.5 and 192.5 months. Weight: L = −0.794905, M = 60.921178, S = 0.172810, z = −0.0887, percentile 46.5. Height: L = 2.125774, M = 173.505721, S = 0.043182, z = 0.2004, percentile 57.9. BMI = 60 ÷ 1.75² = 19.6.
Other questions people ask
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.