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Height Percentile Calculator

CDC growth chart percentile and z-score by age and sex, ages 2 to 20

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Last updated October 2026

Method: The official CDC 2000 stature-for-age LMS parameters (file statage.csv, boys and girls separately) are embedded verbatim. CDC lists each month of age at its half-month point, so an age in completed years and months uses that month's row (9 years 6 months is the 114.5-month row), from 2 years 0 months to 19 years 11 months. The z-score is z = ((height ÷ M)L − 1) ÷ (L × S), converted to a percentile with the standard normal distribution.

Included: Height percentile, z-score, how many children out of 100 are shorter and taller, the CDC median for that exact age and sex, and the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th and 97th percentile heights in feet, inches and centimeters.

Not included: Adult height prediction, weight or BMI percentiles, bone-age assessment, charts for children under 2, WHO growth standards, and any medical diagnosis. A percentile is a screening number, not medical advice.

years
months

Enter completed years and months, for example 9 years 6 months.

ft
in

Measure without shoes, heels and back against a wall, eyes looking straight ahead. Read to the nearest quarter inch (or 0.1 cm).

Height percentile (CDC stature-for-age)

55.1st percentile
Boy · 9 yr 6 mo · 4 ft 6 in (137.2 cm)
Taller than
55 of 100
Shorter than
45 of 100
Z-score
+0.13
Median for this age
4 ft 5.75 in
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Average height for age

Straight through the middle of the CDC chart. Half of all children fall between the 25th and the 75th percentile.

This height is 0.3 in above the CDC median of 4 ft 5.75 in for a boy of 9 years 6 months.

CDC percentile heights at this exact age

What a boy of 9 yr 6 mo measures at each CDC percentile. Your entry sits at the 55th percentile.

PercentileHeightInchesCentimeters
3rd4 ft 1 in49.1124.6
5th4 ft 1.5 in49.6126.0
10th4 ft 2.5 in50.5128.3
25th4 ft 4 in52.0132.1
50th (median)4 ft 5.75 in53.7136.3
75th4 ft 7.5 in55.4140.7
90th4 ft 9 in57.0144.7
95th4 ft 10 in57.9147.1
97th4 ft 10.5 in58.5148.6

The LMS values behind this result

Age used
114.5 months
L (Box-Cox power)
0.4610
M (median, cm)
136.33
S (coefficient of variation)
0.04690

Z is computed as z = ((height / M)^L − 1) / (L × S), then converted to a percentile with the standard normal distribution. CDC lists each month of age at its half-month point, so the row for the completed month is used: 9 years 6 months is the 114.5-month row.

Screening tool, not medical advice. Percentiles come from the CDC 2000 growth charts for U.S. children from age 2 up to the 20th birthday. A single measurement says far less than a growth line tracked over several visits. Discuss any concern about growth with a pediatrician.

Height percentile calculator: how to read a growth chart

A height percentile calculator answers one question: out of 100 children of the same age and sex, how many are shorter than this child? A boy of 9 years 6 months measuring 4 ft 6 in lands at the 55.1st percentile, so he is taller than about 55 of every 100 boys his age. It works like a growth chart calculator for height: the number comes straight from the CDC growth charts, not from a rule of thumb.

Three sister tools cover the neighboring questions. Use the Height Calculator when you want a projection of adult height from the parents' heights instead of a ranking of today's measurement. Use the BMI Calculator for Kids when the concern is weight relative to height rather than height itself. Use the BMI Calculator once the person is 20 or older and the pediatric charts no longer apply. This page is the right one when you have a child's age, sex and a tape-measure reading and you want to know where that reading sits on the CDC curve.

How the percentile is calculated

Heights at a given age are not distributed symmetrically, so the CDC does not simply take a mean and a standard deviation. It publishes three parameters for every month of age (listed at the half-month point) and each sex, a method known as LMS: L is a Box-Cox power that removes skew, M is the median height in centimeters, and S is the coefficient of variation. The measurement is converted to a z-score with:

z = ((X ÷ M)L − 1) ÷ (L × S)

where X is the measured height in centimeters. When L happens to be zero the formula collapses to z = ln(X ÷ M) ÷ S. The z-score is then read off the standard normal distribution to get a percentile: z = 0 is the 50th percentile, z = +1 is the 84.1st, z = +2 is the 97.7th, z = −1 is the 15.9th and z = −2 is the 2.3rd. Running the formula backwards gives the height at any chosen percentile:

X = M × (1 + L × S × z)1/L

That second formula is what fills the reference table in the calculator, so you can see not only where a child sits but what the 5th, 50th and 95th percentile heights are for that exact age.

Worked example: a boy of 9 years 6 months at 4 ft 6 in

Take a boy aged 9 years 6 months, which is 114 completed months and therefore the CDC row for 114.5 months (it covers 114.0 up to 115.0 months), measuring 4 ft 6 in. First convert: 4 ft 6 in is 54 inches, and 54 × 2.54 = 137.16 cm. The CDC boys' stature-for-age parameters for that row are L = 0.461031, M = 136.334 cm and S = 0.046897.

Now apply the formula. The ratio X ÷ M is 137.16 ÷ 136.334 = 1.006057. Raised to the power L that becomes 1.0060570.461031 = 1.002788. Subtract 1 to get 0.002788, then divide by L × S = 0.461031 × 0.046897 = 0.021621. The result is a z-score of +0.1289. Feeding that into the standard normal distribution gives 55.13%, so this boy is at the 55.1st percentile: taller than roughly 55 of every 100 boys aged 9 years 6 months, shorter than about 45 of them. The median for his age is 136.33 cm, which is 4 ft 5.75 in, so he is about 0.3 in above the middle of the chart.

Second example: a girl of 13 at 5 ft 2 in

A girl who has just turned 13 (156 completed months, so the 156.5-month row) measuring 5 ft 2 in gives 62 inches, or 157.48 cm. The CDC girls' parameters for that row are L = 1.242968, M = 157.344 cm and S = 0.043859. The z-score works out to +0.020, which is the 50.8th percentile. She is a hair above the median for her age, 157.34 cm or 61.95 in, which rounds to 5 ft 2 in. Note how different the same 5 ft 2 in reading looks two years earlier or later: at 11 it would be the 96.4th percentile, at 15 only the 24.8th. The measurement did not change; the reference group did.

CDC height percentiles for boys, ages 2 to 20

All values below are computed from the CDC stature-for-age LMS parameters for the age shown in completed years and months, using CDC's half-month row (10 yr means 10 years 0 months, the 120.5-month row), and rounded to the nearest quarter inch, exactly as the calculator shows them. The last row, 19 years 11 months, is the final month on the chart.

Age 5th 25th 50th 75th 95th
2 yr2 ft 8 in2 ft 9.25 in2 ft 10.25 in2 ft 11.25 in3 ft 0.5 in
4 yr3 ft 1.75 in3 ft 3.25 in3 ft 4.25 in3 ft 5.5 in3 ft 7 in
6 yr3 ft 6.25 in3 ft 8.25 in3 ft 9.5 in3 ft 10.75 in4 ft 0.75 in
8 yr3 ft 10.75 in4 ft 1 in4 ft 2.5 in4 ft 4 in4 ft 6.25 in
10 yr4 ft 2.5 in4 ft 5 in4 ft 6.75 in4 ft 8.5 in4 ft 11 in
12 yr4 ft 6 in4 ft 8.75 in4 ft 10.75 in5 ft 0.75 in5 ft 3.75 in
14 yr4 ft 11.25 in5 ft 2.5 in5 ft 4.5 in5 ft 6.75 in5 ft 9.75 in
16 yr5 ft 3.25 in5 ft 6.25 in5 ft 8.25 in5 ft 10.25 in6 ft 1 in
18 yr5 ft 4.75 in5 ft 7.5 in5 ft 9.25 in5 ft 11.25 in6 ft 2 in
19 yr 11 mo5 ft 5 in5 ft 7.75 in5 ft 9.5 in5 ft 11.5 in6 ft 2.25 in

The spread widens through childhood and then narrows again: the gap between the 5th and 95th percentile is 4.5 in at age 2, 8.6 in at age 10, 10.4 in at age 14 when boys are in the middle of their growth spurt, and 9.3 in at age 18.

CDC height percentiles for girls, ages 2 to 20

Same method, girls' curves. Notice that the girls' chart flattens out roughly two years before the boys' chart does.

Age 5th 25th 50th 75th 95th
2 yr2 ft 7.25 in2 ft 8.75 in2 ft 9.5 in2 ft 10.5 in3 ft 0 in
4 yr3 ft 1 in3 ft 2.75 in3 ft 3.75 in3 ft 5 in3 ft 6.75 in
6 yr3 ft 6 in3 ft 8 in3 ft 9.25 in3 ft 10.75 in4 ft 0.75 in
8 yr3 ft 10.75 in4 ft 0.75 in4 ft 2.25 in4 ft 4 in4 ft 6.25 in
10 yr4 ft 2.25 in4 ft 4.75 in4 ft 6.5 in4 ft 8.25 in4 ft 11 in
12 yr4 ft 6.75 in4 ft 9.75 in4 ft 11.75 in5 ft 1.5 in5 ft 4.25 in
14 yr4 ft 11 in5 ft 1.5 in5 ft 3.25 in5 ft 5 in5 ft 7.5 in
16 yr4 ft 11.75 in5 ft 2.25 in5 ft 4 in5 ft 5.75 in5 ft 8.25 in
18 yr5 ft 0 in5 ft 2.5 in5 ft 4.25 in5 ft 6 in5 ft 8.5 in
19 yr 11 mo5 ft 0 in5 ft 2.5 in5 ft 4.25 in5 ft 6 in5 ft 8.5 in

The two charts cross twice. At age 10 the medians differ by a quarter inch, at 11, 12 and 13 the median girl is taller (by 0.2 in, 0.9 in and 0.4 in), and from 14 onward the boys pull ahead: 1.4 in at 14, 4.3 in at 16 and 5.3 in at 19 years 11 months.

Why the same height moves down the chart every year

This is the single most confusing part of growth charts for parents, so it is worth a table of its own. Below is the percentile of a child measuring exactly 5 ft 0 in at different ages, computed from the same LMS parameters.

Age at measurement Percentile, boy Percentile, girl
9 years99.899.8
10 years97.897.9
11 years88.886.6
12 years66.054.9
13 years30.523.8
14 years7.711.0
15 years1.77.1

A child who simply stops growing does not hold a percentile, they fall through the chart. The median 10-year-old boy is 4 ft 6.75 in; if he measures the same 4 ft 6.75 in at 11 he is at the 25th percentile, and at 12 he is down at the 8th. That is the mechanism behind almost every worried search for a height percentile calculator, and it is why pediatricians look at the slope of the line rather than any single dot.

How to use this height percentile calculator

  1. Pick the sex. Boys and girls have separate CDC curves and the difference is large in the teenage years, so this is not a cosmetic choice.
  2. Enter the age in years and months. Months matter: at 9 years 0 months, 4 ft 6 in is the 70.9th percentile, but at 9 years 6 months the same reading is the 55.1st. Count completed years and months from the birth date to the measurement date.
  3. Choose your units. Feet and inches is the default; switch to centimeters if that is what your tape or clinic uses.
  4. Enter the standing height. Shoes off, heels and back to the wall, eyes level and looking straight ahead, read to the nearest quarter inch or 0.1 cm.
  5. Read the percentile and the z-score. The headline number is the percentile; the z-score below it is the same result in standard deviations, which is what most clinical notes record.
  6. Scan the reference table. It shows the 3rd through 97th percentile heights for that exact age and sex, so you can see how far a quarter inch or a birthday actually moves things.

Who this calculator is for

  • Parents who came home from a well-child visit with a number on a chart and want to check it or track it between appointments.
  • Teens curious how their own height compares with others their age, in a way that a single national average cannot answer.
  • Coaches and school nurses grouping children by growth stage rather than by grade.
  • Anyone comparing siblings at the same age, which only works once you convert raw inches into percentiles.
  • Students learning how LMS parameters and z-scores turn a measurement into a percentile.

Key terms explained

  • Percentile: the share of the reference population that is shorter. The 30th percentile means 30 of 100 same-age, same-sex children are shorter and 70 are taller.
  • Z-score: the same result in standard deviations. Zero is the median, +1.64 is the 95th percentile, −1.64 is the 5th.
  • Stature-for-age: the CDC's name for the standing-height chart used from age 2. Before age 2 the equivalent chart is length-for-age, measured lying down.
  • LMS parameters: the three numbers (skew, median, variation) the CDC publishes for every age and sex, which is what makes an exact percentile possible instead of a lookup between printed curves.
  • Percentile channel: the band between two printed curves. Healthy growth normally tracks along one channel rather than crossing several.
  • Growth velocity: inches gained per year. It is a different measurement from percentile and often the more informative one.

What changes the result the most

  • Age in months. The steeper the curve, the more a few months matter. A boy of 4 ft 6 in is at the 70.9th percentile at 9 years, the 55.1st at 9 years 6 months and the 40.0th at 10 years.
  • Measurement precision. At 9 years 6 months, half an inch moves a boy from the 47.2nd to the 55.1st to the 62.8th percentile. Slouching or leaving shoes on will swamp any other error.
  • Sex. The same 54 in at 9 years 6 months is the 55.1st percentile for a boy and the 59.3rd for a girl, and the gap grows sharply after age 13.
  • Timing of puberty. An early or late growth spurt moves a child several percentile channels without anything being wrong; boys gain about 3.04 in between 13 and 14, and girls about 2.84 in between 11 and 12.
  • Time of day. Spinal discs compress over the course of a day, so an evening measurement can come in noticeably shorter than a morning one. Measure at the same time of day when tracking.

Median growth per year, and why it matters

Percentiles hide velocity, so it helps to know roughly how much growth is normal at each age. Computed from the CDC medians, boys gain about 3.31 in between ages 2 and 3, 2.51 in between 6 and 7, a slow 1.93 in between 10 and 11, then a peak of 3.04 in between 13 and 14 before dropping to 0.68 in between 16 and 17. Girls follow the same shape about two years earlier: 3.47 in between 2 and 3, 2.38 in between 10 and 11, a peak of 2.84 in between 11 and 12, then just 0.56 in between 14 and 15 and 0.14 in between 16 and 17. A child growing far less than these figures for their age, even at a comfortable percentile, is the pattern worth raising with a pediatrician.

Tips for an accurate measurement

  • Take shoes and bulky hair accessories off, and flatten braids or a topknot.
  • Stand on a hard floor, not carpet, with heels together and touching the wall.
  • Line up the back of the head, shoulder blades, buttocks and heels against the wall where the child's posture allows it.
  • Have the child look straight ahead so the chin is level, then bring a flat object down onto the crown at a right angle to the wall.
  • Mark the wall, measure from the floor with a steel tape, and read to the nearest quarter inch or 0.1 cm.
  • Measure twice. If the two readings differ by more than a quarter inch, measure a third time and average.

When a percentile is worth a doctor's visit

A percentile is a screening number, and a low or high one is not a diagnosis. The situations clinicians generally want to see are a height persistently below the 3rd percentile, a height far out of line with the family pattern, a fall across two or more percentile channels over a year or two, growth that has clearly slowed or stopped before the teenage years are over, or a very early or very late growth spurt. Bring the whole growth record, not one reading, and note whether the parents were also late bloomers. If nothing else, plotting several measurements over time answers most of the questions a single percentile raises.

Limitations and assumptions

  • The CDC 2000 charts describe U.S. children measured in national surveys between 1963 and 1994. They are a reference for how American children grew, not a standard for how any child should grow.
  • The chart covers 2 years 0 months to 19 years 11 months only. Under 2, recumbent length and, in the U.S., the WHO growth standards are used instead; at the 20th birthday the chart ends.
  • The percentile is height alone. It says nothing about weight, body composition, bone age or pubertal stage, all of which a clinician weighs alongside it.
  • The charts are not broken out by ancestry, and a single national reference will not fit every family's genetic background equally well.
  • Ages are entered in completed years and months, and each month uses the CDC row listed at its half-month point (the 114.5-month row covers 114.0 up to 115.0 months). That is how CDC's own SAS program treats completed months, and it keeps the age error within about 15 days.
  • Children with certain genetic or chronic conditions are followed on condition-specific charts, not the general CDC chart.

How it compares to related calculators

This page ranks a height that has already been measured. If your question is different, a sister tool fits better:

  • To estimate how tall a child will end up from the parents' heights, use the Height Calculator.
  • To score weight against height for a child or teen, use the BMI Calculator for Kids, which uses the matching CDC BMI-for-age chart.
  • Once a person is 20 or older, switch to the adult BMI Calculator with its fixed 18.5, 25 and 30 cutoffs.
  • For a healthy adult weight range at a given height, use the Ideal Weight Calculator.
  • For body composition rather than size, use the Body Fat Calculator.

💡 Good to know

The trend beats the number

One measurement gives a dot; three or four over a year give a line. A child tracking steadily along the 15th percentile is usually growing exactly as expected. A child falling from the 60th to the 20th in eighteen months has crossed curves, and that is the pattern worth a conversation, even though both children may look fine on any single day.

Girls are ahead for about two and a half years

Between roughly ages 11 and 13 the median girl on the CDC chart is taller than the median boy, because girls start their growth spurt earlier. At 12 the medians are 4 ft 11.75 in for girls and 4 ft 10.75 in for boys. By 16 the median boy is 4.3 in taller. Comparing a boy against girls in his class, or the other way round, will always mislead.

The 5th percentile is not a failing grade

Five percent of perfectly healthy children are at or below the 5th percentile, by definition, and most of them are short because their parents are short. The CDC calls a percentile a screening indicator. It flags a measurement for a closer look; it does not decide anything by itself.

⚠️ Common mistakes & edge cases

Rounding the age to whole years

The curve moves every month. For a boy at 4 ft 6 in, entering 9 years instead of 9 years 6 months changes the answer from the 55.1st to the 70.9th percentile. Always enter the months.

Measuring with shoes on or against carpet

Both add height, and half an inch is worth about eight percentile points for a 9-year-old. Shoes off, hard floor, heels to the wall, eyes level, read to the quarter inch.

Panicking when the percentile drops

A percentile falls whenever a child grows more slowly than the reference for a while, which is exactly what happens to a late bloomer just before a growth spurt. The median 10-year-old boy who does not grow at all for a year lands at about the 25th percentile at 11. Look at the growth line, not the single drop.

Comparing a percentile against the wrong sex

The same 54 in at 9 years 6 months is the 55.1st percentile for a boy and the 59.3rd for a girl, and after age 13 the two charts pull far apart. Comparing a child against classmates of the other sex will always give the wrong impression.

Confusing a percentile with an adult-height prediction

A height percentile ranks today's measurement. It is not a forecast. Children often finish near the channel they tracked along, but for an actual estimate use the mid-parental method in the Height Calculator.

Using the CDC chart for a toddler under 2

The stature-for-age chart starts at 24 months and needs a standing measurement. Below that age, length is measured lying down and a different chart applies, so this calculator will not return a result.

Note: A height percentile is a screening number, not a diagnosis or medical advice. Talk to a pediatrician about any concern regarding a child's growth.

❓ Frequently asked questions

How is a height percentile calculated?

The CDC publishes three numbers for every age and sex on the stature-for-age chart: L (a skew parameter), M (the median height in centimeters) and S (a coefficient of variation). Your child's height is turned into a z-score with z = ((height / M)^L - 1) / (L x S), and the z-score is converted to a percentile with the standard normal distribution. A boy of 9 years 6 months measuring 4 ft 6 in has a z-score of +0.13, which is the 55.1st percentile.

What does the 50th percentile mean for height?

It means exactly half of U.S. children of the same age and sex are shorter and half are taller. It is the median of the reference population, not a target. At 10 years 0 months the CDC median is 4 ft 6.75 in for boys and 4 ft 6.5 in for girls. A child at the 30th percentile and a child at the 70th percentile are both perfectly normal; the number describes a position in a group, not a grade.

What age range does this height percentile calculator cover?

Ages 2 years 0 months through 19 years 11 months, for boys and girls separately. That is the span of the CDC stature-for-age charts for ages 2 to 20, which end at the 20th birthday: CDC's own SAS program scores height-for-age only below 240 months. Below age 2, clinicians measure recumbent length rather than standing height and use a different chart, and in the United States the WHO growth standards are recommended for children under 2.

Is a low height percentile a problem?

Not on its own. Someone has to be at the 5th percentile, and most children there are simply short because their parents are short. What matters more is the trend: a child who has tracked along the 10th percentile for years is usually growing normally, while a child who drops from the 50th to the 10th over two years has crossed curves and should be seen. Clinicians commonly flag heights below the 3rd percentile or a fall of more than about two percentile channels for a closer look.

Why did my child's percentile change without losing height?

Because the reference curve moves with every month of age. The median boy of 10 years 0 months is 4 ft 6.75 in tall, and that same height at 11 years 0 months is only the 25th percentile, at 12 years 0 months the 8th. Children who have not started their growth spurt slide down the chart while their peers shoot up, then climb back once their own spurt arrives. That is why a single reading tells you far less than a line drawn through several visits.

Do boys and girls use different height charts?

Yes, and the difference is not constant. At age 10 the medians are within a quarter inch of each other, and between ages 11 and 13 the median girl is actually taller than the median boy because girls enter puberty first. By age 14 the median boy is 1.4 in taller, and by age 18 the gap is 5.1 in. Entering the wrong sex therefore shifts the percentile, most of all through the teenage years.

How accurate does the height measurement need to be?

More accurate than most people expect. For a boy of 9 years 6 months, 4 ft 5.5 in is the 47.2nd percentile, 4 ft 6 in is the 55.1st and 4 ft 6.5 in is the 62.8th. Half an inch moves the answer by roughly eight percentile points at that age. Measure with shoes off, heels and back against a wall, eyes looking straight ahead, and read to the nearest quarter inch.

What is a height z-score?

The z-score is the same result expressed in standard deviations instead of a percentile. Zero is exactly the median, +1 is the 84.1st percentile, +2 is the 97.7th, -1 is the 15.9th and -2 is the 2.3rd. Clinicians often track z-scores because at the extremes the percentiles bunch together: the difference between the 98th and 99th percentile looks tiny but is a large move in z.

Does this calculator predict how tall my child will be?

No. It scores the height measured today against children of the same age and sex; it does not project an adult height. For a family-based estimate, the mid-parental height method uses the parents' heights instead, and our Height Calculator applies it. Children usually finish close to the percentile channel they have tracked along, but that is a pattern, not a prediction.

Can adults use a height percentile calculator?

The CDC stature-for-age chart ends at the 20th birthday (240 months), so 19 years 11 months is the last age this tool can score. At that age the CDC median is 69.6 in for young men and 64.3 in for young women. Most people have finished growing well before then, so the end of the chart is a reasonable reference for a young adult, but the chart is not designed for adults and no result is offered from age 20.

What does 'crossing percentile lines' mean?

The growth chart is drawn as a set of curves (3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th). Healthy children usually stay roughly parallel to one of them. Crossing downward through two or more of those lines over a year or two, or shooting upward through them, is the pattern pediatricians watch for, because it can point to nutrition, hormone or chronic-illness issues that a single measurement would hide.

Does this height percentile calculator work in metric units?

Yes. It defaults to feet and inches and has a centimeter toggle. The CDC LMS parameters are metric, so US entries are converted to centimeters before the z-score is computed, and results are shown both ways: 4 ft 6 in and 137.16 cm produce the same percentile. Switching the toggle converts the height you have entered (4 ft 6 in becomes 137.2 cm) and keeps the exact value, so the result does not change.

Which growth chart does this calculator use?

The CDC 2000 growth charts, stature-for-age, ages 2 to 20 years, using the official L, M and S parameters from the CDC file statage.csv, embedded verbatim. CDC lists each month of age at its half-month point (the 114.5-month row covers 114.0 up to 115.0 months), so a child of 9 years 6 months is scored on the 114.5-month row. CDC's own SAS program handles ages in completed months the same way, by adding half a month.

Is this calculator free to use?

Yes. There is no sign-up, no fee and no limit on how many children or how many measurements you can run. Nothing is transmitted anywhere: the LMS table is embedded in the page and every calculation happens in your own browser.

📚 Sources

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