Enter your child's age, sex and height to see where they stand on the CDC stature-for-age growth chart: the percentile, the z-score, the median height for their age and a plotted growth curve. Everything is calculated in your browser.
Last updated:
Units
Sex
Age from
yr
mo
ft
in
cm
Standing height without shoes.
Enter your values to see the result.
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How to use the Child Height Percentile Calculator
Choose units and sex: US (feet and inches) or metric (cm), and boy or girl.
Enter the age in years and months, or switch to birth date for an exact age on the day measured.
Enter the height measured standing, without shoes.
Press Calculate height percentile to see the percentile, z-score and median height.
Check the growth chart to see the point against the percentile curves, and download the percentile table as CSV if you want to keep it.
How the height-for-age percentile is worked out
The CDC growth charts summarize the heights of a large reference sample of US children with three smooth numbers for every age: the median height M, the coefficient of variation S (how spread out heights are) and the skewness term L. Your child's height is turned into a z-score with the LMS formula, and the z-score is turned into a percentile using the normal distribution.
z = ((height ÷ M)L − 1) ÷ (L × S) and percentile = Φ(z) × 100
For example, a 7-year-old boy who is 120 cm tall: the reference median is about 121.9 cm with S ≈ 0.0428, so z = (120 ÷ 121.9 − 1) ÷ 0.0428 ≈ −0.36, which is about the 36th percentile.
Median height by age (CDC 50th percentile)
Approximate median standing height for US children. Half of children are taller and half shorter than these values.
Age
Boys (cm)
Boys (ft-in)
Girls (cm)
Girls (ft-in)
2 years
86.5
2′ 10″
85.0
2′ 9.5″
4 years
102.5
3′ 4.4″
101.6
3′ 4″
6 years
115.5
3′ 9.5″
115.0
3′ 9.3″
8 years
128.0
4′ 2.4″
127.0
4′ 2″
10 years
138.4
4′ 6.5″
138.6
4′ 6.6″
12 years
149.1
4′ 10.7″
151.2
4′ 11.5″
14 years
163.8
5′ 4.5″
159.8
5′ 2.9″
16 years
173.4
5′ 8.3″
162.5
5′ 4″
18 years
176.1
5′ 9.3″
163.1
5′ 4.2″
20 years
176.8
5′ 9.6″
163.3
5′ 4.3″
Notice that girls are briefly taller than boys around ages 11 to 13, because girls usually start their pubertal growth spurt about two years earlier.
Tips for an accurate measurement
Measure barefoot, heels, buttocks and shoulders against a wall, looking straight ahead.
Lay a hardback book flat on the head, square to the wall, and mark where its lower edge meets the wall.
Measure at the same time of day each time; children are slightly taller in the morning.
Track measurements every few months. A steady curve says more than any single percentile.
Frequently asked questions
What does a height percentile mean?
A height percentile compares a child with others of the same age and sex. A child at the 40th percentile is taller than about 40 out of 100 children of that age and shorter than about 60. It is a comparison, not a grade: any percentile between the 5th and 95th is in the usual range.
Which growth chart does this calculator use?
It uses the CDC 2000 stature-for-age reference for boys and girls aged 2 to 20, which US pediatricians use from age 2. The reference median and spread are stored at half-year steps and interpolated for the exact age; the LMS skewness term is set to 1 because it is very close to 1 for height, so results match the official charts to within a fraction of a percentile point in nearly all cases.
How is the z-score calculated?
With the LMS method: z = ((height ÷ M)^L − 1) ÷ (L × S), where M is the median height for the age, S the coefficient of variation and L the skewness term. The percentile is the standard normal cumulative probability of z. A z-score of 0 is the median, −1 is about the 16th percentile and +2 is about the 98th.
When is a height percentile a concern?
Doctors usually look more closely when a child is below the 3rd or 5th percentile, above the 95th or 97th, or when a child crosses two or more major percentile lines over time. A single measurement within the normal range is rarely a concern, and short or tall parents often have children who track low or high. Ask your pediatrician about any worry.
Why does my child's percentile change between visits?
Small changes are normal because of measuring differences (shoes, posture, time of day) and natural growth spurts. Percentiles also shift around puberty because children start it at different ages: an early developer can look tall at 11 and average at 16. What matters is the overall trend.
Can I use this for a child under 2?
No. The CDC recommends the WHO growth standards for babies and toddlers under 2, which measure lying-down length rather than standing height. Use the Baby Percentile Calculator for ages 0 to 24 months.
Is this a medical diagnosis?
No. It is an information tool that reproduces the public CDC reference curves. Growth assessment depends on repeated measurements, family height, puberty stage and overall health, so discuss results with your child's doctor.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.