Height Percentile Calculator for Kids

The height percentile calculator shows how tall a child or teen is compared with others of the same sex and age, using the CDC stature-for-age charts for ages 2 to 20. Enter age, sex and height to get the percentile, z-score, median height for age and an optional parent-based adult height estimate.

How to use the Height Percentile Calculator for Kids

1. Select boy or girl.
2. Enter the child's age in years plus extra months (2 to 20 years).
3. Enter the measured height and choose the unit; for feet and inches put feet in the height box and inches in the extra inches box.
4. Optionally enter both parents' heights for a mid-parental target height.
5. Press Calculate to read the percentile, the median for age and the 3rd to 97th range.

Formula and method

The CDC publishes L, M and S values for stature-for-age in 0.5-month steps from age 2 to 20. The calculator interpolates them to the child's exact age, then computes z = ((height / M)^L − 1) / (L × S) and converts z to a percentile with the normal distribution. For stature the L value is close to 1, so heights are nearly normally distributed at each age.

The optional parent-based estimate uses the mid-parental formula: (mother's height + father's height ± 13 cm) / 2, adding 13 cm for a boy and subtracting 13 cm for a girl. Most children finish within about 8.5 cm of this target, though the range is wide.

Height by age for boys: 3rd to 97th percentile

Height at key percentiles from the CDC LMS tables, in centimeters and inches.

Height by age for girls: 3rd to 97th percentile

Height at key percentiles from the CDC LMS tables, in centimeters and inches.

What is a normal height percentile?

Every percentile from the 3rd to the 97th is within the usual range. The 50th percentile is the median, not a target. A child at the 20th percentile is not behind and a child at the 90th is not ahead: they are tracking along their own growth curve. The pattern over time is what matters. Children usually follow a similar percentile channel after about age 2 to 3, apart from changes at puberty.

How parents' height affects a child's height

Genes are the largest influence on adult height. That is why the parent-based estimate is shown in addition to the percentile. If a child's percentile is far from the mid-parental target percentile, it is worth mentioning to a doctor, but late growers and early growers often settle near their parents' heights.

Puberty and growth spurts

Children grow about the same amount each year in the middle childhood years and then speed up during the pubertal growth spurt. Girls usually start the spurt earlier than boys, which can briefly move a girl up and a boy down the percentile chart relative to peers. Late bloomers often cross percentile lines upward in the later teen years.

When a height percentile may need a doctor

See a pediatrician if the child is below the 3rd or above the 97th percentile, if height has dropped across two or more major percentile lines, if growth seems to have stalled for 6 to 12 months, or if there are other symptoms such as long-lasting tiredness, poor appetite or very early or late signs of puberty. Growth hormone problems, thyroid disease, celiac disease and other conditions can affect height, but most short or tall children are healthy.

How to measure height accurately

Measure without shoes, with the heels, buttocks and shoulders against a flat wall, eyes looking straight ahead, and mark the top of the head with a flat object held level. Measure at the same time of day if possible, because height can vary by a centimeter or more between morning and evening. Children under 2 are measured lying down, which is why they use the Baby Growth Percentile Calculator.

CDC charts and WHO charts

This tool uses the CDC 2000 charts from ages 2 to 20. The WHO growth standards are recommended from birth to 24 months. The two reference sets differ slightly where they overlap at age 2 because WHO describes optimal growth in a healthy, mostly breastfed sample while CDC describes how U.S. children grew in the reference period.

Frequently asked questions

What percentile is average height?

The 50th percentile is the median height for the age and sex. Anything from the 3rd to 97th percentile is within the usual range.

Does the percentile predict adult height?

Only roughly. If a child stays on the same percentile, the age-20 line shows where that would land. Puberty timing and genetics can change this, so it is a rough guide.

How is mid-parental height calculated?

Add the mother's and father's heights, add 13 cm for a boy or subtract 13 cm for a girl, then divide by 2. Most children land within about 8.5 cm of the result.

What if my child is below the 3rd percentile?

Many healthy children are. A pediatrician can look at growth history, family heights and puberty stage and decide if any tests are needed.

Can I use this for a baby?

Not under age 2. Use the Baby Growth Percentile Calculator or the baby length calculator, which use the WHO standards.

Are boys and girls compared separately?

Yes. The CDC publishes separate L, M and S values for boys and for girls.

Sources

• CDC: Growth chart percentile data files with LMS values
• Kuczmarski RJ et al. 2000 CDC Growth Charts for the United States: methods and development (NCHS Vital and Health Statistics, Series 11, No. 246)
• CDC: Child and Teen BMI Calculator

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