Height percentile calculator

What a height percentile means

A height percentile compares one person with a large reference group of the same sex and age. If a 10-year-old boy is on the 70th percentile, he is taller than about 70 out of 100 boys his age and shorter than about 30. The 50th percentile is the median, the middle height. A percentile is not a grade: the 20th percentile is not "worse" than the 80th, just shorter.

Behind each percentile is a z-score, the number of standard deviations above or below the median. A z-score of 0 is the 50th percentile, +1 is about the 84th, and -2 is about the 2nd. Doctors often use z-scores because they still work at the extremes, where percentiles bunch up near 0 and 100.

How this height percentile calculator works

Growth charts are published as three numbers for every month of age, called L, M and S. M is the median height, S is the spread, and L corrects for any skew. The calculator looks up L, M and S for the exact age you enter, computes the z-score with the standard LMS formula, z = ((height / M)^L - 1) / (L × S), and converts that to a percentile. This is the same method the CDC and WHO use in their own software, so the results match the printed charts. We checked every printed percentile in the source files and the calculator reproduces each one.

For adults, there is no growth curve, so the calculator compares your height with measured heights of US adults from the CDC's NHANES survey (2015 to 2018), interpolating between the published percentiles. You can compare with all adults or with your own age group, which matters because older adults are a little shorter on average.

CDC or WHO: which growth chart?

There are two main sets of children's growth charts. The WHO Child Growth Standards were built from healthy, breastfed babies in six countries and show how young children grow in good conditions. The CDC 2000 growth charts describe how American children aged 2 to 20 actually grew in national surveys. The CDC recommends that US doctors use the WHO charts from birth to age 2 and the CDC charts from 2 to 20, and this calculator does the same, switching at 24 months.

That switch is why a child can move a few percentile points at their second birthday without growing any differently. Babies are also measured lying down (length) and older children standing (height), and standing height is usually about 0.7 cm shorter.

Why we built this height percentile calculator

Before building CheckMyHeight, I tested a lot of height and sizing websites to see what people need and what gets in the way. Height percentile tools were a clear case where the details matter. Many give one answer for every age without saying which growth chart they use, even though the WHO and CDC charts differ and the CDC itself recommends switching from one to the other at age 2. Some ask only for the age in years, although a child can grow several centimetres in a year, so a 10-year-old and a 10-and-a-half-year-old are compared with the wrong median. And most stop at childhood, so adults who want to know where they rank get a child chart or nothing.

We wanted one page that uses the official tables in the official way for every age, shows the z-score and the chart instead of a bare number, and says plainly when a result is worth taking to a pediatrician.

What this height percentile calculator measures

It does not measure anyone: you type a height that you measured. From that it calculates:

• Under 24 months: length-for-age from the WHO Child Growth Standards (2006), by completed month.
• 24 months to 20 years: stature-for-age from the CDC 2000 growth charts, using the age in years and months (each CDC row is the middle of its month).
• The z-score with the LMS formula, z = ((height / M)^L - 1) / (L × S), with L, M and S interpolated for the exact age, then converted to a percentile with the normal distribution.
• Adults 20 and over: your height against the measured percentiles of US adults in NHANES 2015-2018 (Fryar et al., 2021), for all adults or your age group, interpolated between the published percentiles.
• Optional weight: weight-for-age from the same WHO or CDC tables, with the WHO rule for values beyond 3 standard deviations.
• For children: the height at age 20 on the same percentile line, drawn on a growth chart with the 5th to 95th percentile curves.

The tables were downloaded from the CDC on 16 October 2026 and last checked on 24 October 2026. What it does not do: it does not track growth over time, it does not judge whether weight suits height (that is BMI-for-age), it does not compare with countries other than the US for adults, and it does not diagnose anything. It is a screening reference, not medical advice.

Why this height percentile calculator is different

• The right chart for the age, WHO under 2 and CDC from 2 to 20, as the CDC recommends, plus measured adult data, all on one page.
• Age in months, not just years, so the median is the one for the child's real age.
• The method is shown: the formula, the reference used for your result and the z-score, so a doctor or parent can check the number.
• Sources are linked to the CDC and WHO files at the end of the page.
• No account and nothing sent. The calculation runs in your browser; height and age are not stored or uploaded.
• The age in years and the height start empty, and no result appears until you enter them.

How to measure a child accurately

A measuring error of 1 cm can move a percentile by several points, so it pays to measure carefully.

• Under 2: measure lying down. Lay the baby on a firm surface, head against a wall or board, legs gently straightened, and mark where the heels are. Two people make this much easier.
• Age 2 and over: measure standing, barefoot, on a hard floor. Heels, bottom and shoulders touch the wall, feet together, looking straight ahead.
• Lower a hardback book flat on the head, mark the wall underneath it, and measure from the floor to the mark with a steel tape.
• Measure twice and use the average. Measure at the same time of day each time, since people are a little taller in the morning.

Our guide to measuring height at home has more detail and photos.

When to talk to a pediatrician

Percentiles are a screening reference, not a diagnosis. A child on the 5th percentile with short parents who grows steadily along that line is usually perfectly healthy. What doctors look for is a pattern: a height below the 3rd or above the 97th percentile, a height far from what the parents' heights suggest, or a child who crosses two or more of the main percentile lines after age 2. If you see any of those, take your measurements to your pediatrician, who can check growth over time and decide whether anything needs a closer look.

To estimate adult height from the parents instead, try the height calculator or the mid-parental height calculator.

Height percentiles for US adults

Measured heights of adults aged 20 and over, from the CDC's NHANES survey (2015 to 2018). Read across: 25% of men are shorter than 5′ 7″ and 75% of women are shorter than 5′ 5½″.

Mean: men 175.3 cm, women 161.3 cm. A 5′ 4″ woman is taller than about 57% of US women. For averages around the world, see average height.

Average height by age for children

The 50th percentile (median) height at each age, from the WHO standards under 2 and the CDC charts from 2.

Sources

• CDC 2000 growth charts, stature-for-age and weight-for-age LMS data (statage.csv, wtage.csv), ages 2 to 20: CDC growth chart data files.
• WHO Child Growth Standards (2006), length-for-age and weight-for-age, birth to 24 months, as distributed by the CDC (NCHS); see also WHO child growth standards.
• Fryar CD, Carroll MD, Gu Q, Afful J, Ogden CL. Anthropometric reference data for children and adults: United States, 2015-2018. Vital Health Stat 3(46), 2021. Tables 9 and 11.
• CDC guidance on using the WHO growth charts for children under 2.

Questions