Height Age Calculator - Is Your Child Tall Enough for Their Age?

Date of Birth

Measurement Date

Sex

Height (cm)

Weight (kg, optional)

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📊 Height Age Results

📖 How to Measure Height Correctly

A height age is only as good as the measurement behind it. A wobbly reading taken with shoes on can shift a percentile by 10 points, which is why clinics repeat measurements before referring a child. Use the same method every time so your numbers stay comparable:

Under 2 years: measure lying down with a length board, heels against the base, knees gently flattened. Recumbent length runs about 1 cm longer than standing height.
2 years and older: stand the child against a wall or door frame with heels, buttocks, shoulder blades and the back of the head touching the surface.
Head position: look straight ahead in the Frankfurt plane - the line from the eye corner to the top of the ear should be level.
Feet and hair: barefoot, heels together, and flatten any thick hair or take out a ponytail that adds height.
Timing: measure in the morning if possible. Children are roughly 0.5 to 1 cm taller before the spine compresses during the day.
Repeat: take two readings and average them. If they differ by more than 0.5 cm, take a third.

📊 Median Height by Age (2-18 Years)

Use this reference chart to sanity-check the calculator output. Values are the median (50th percentile) standing heights rounded to the nearest centimetre, based on CDC and WHO growth reference data. Roughly 50 percent of healthy children the same age fall below these numbers and 50 percent above.

Median standing heights, rounded. Girls reach their adult height near age 14-15; boys near 17-18.
Age	Boys Median	Inches	Girls Median	Inches
2	87 cm	34 in	86 cm	34 in
3	96 cm	38 in	95 cm	37 in
4	103 cm	41 in	102 cm	40 in
5	110 cm	43 in	109 cm	43 in
6	116 cm	46 in	115 cm	45 in
7	122 cm	48 in	121 cm	48 in
8	128 cm	50 in	127 cm	50 in
9	133 cm	52 in	132 cm	52 in
10	138 cm	54 in	138 cm	54 in
11	143 cm	56 in	144 cm	57 in
12	149 cm	59 in	151 cm	59 in
13	156 cm	61 in	157 cm	62 in
14	163 cm	64 in	160 cm	63 in
15	169 cm	67 in	162 cm	64 in
16	173 cm	68 in	163 cm	64 in
17	175 cm	69 in	163 cm	64 in
18	176 cm	69 in	164 cm	65 in

Two patterns stand out in the table. Girls overtake boys briefly around age 11-12 because their pubertal growth spurt starts roughly two years earlier, then boys who mature later pass them again by 14 and finish 12 to 13 cm taller on average. A child who sits at the 25th percentile and stays on that line is growing normally, even though the raw number looks small.

💡 Who Uses a Height Age Calculator

👨‍👩‍👧 Parents tracking growth

Families log heights every birthday or every school year to see whether a child is holding their percentile line. Steady tracking matters more than any single reading, because crossing percentile lines is the signal pediatricians look for.

🧒 Late bloomers and early developers

A 13-year-old who has not started puberty may read two years short for age while being perfectly on target for bone age. Comparing height age with chronological age shows how much of the gap is simply timing.

🏫 School sports and tryouts

Coaches grouping players by age often end up with huge mismatches. Converting height to a height age shows the spread within a single birth year and helps coaches place children at a fairer level.

🏥 Clinical screening prep

Before a growth clinic appointment, parents can compute height age and BMI-for-age at home so the consultation can focus on symptoms, family history and whether a bone age X-ray is needed.

💊 Medication monitoring

Children on stimulant medication, corticosteroids or growth hormone therapy are measured every 3 to 6 months. A growth rate below 4 cm per year after age 4 is a common trigger for adjusting treatment.

📏 Adult height expectations

Mid-parental height converts both parents' heights into a realistic adult target with an 8.5 cm normal range. It reframes the question from "is my child short?" to "is my child short for this family?"

⚙️ How the Calculation Works

The calculator converts your measurement into a growth-standard age and a percentile in four steps:

Age at measurement: the exact years and decimal months between the birth date and the measurement date, so a measurement taken early or late in the year does not skew the result.
Height age: the age at which your height equals the median, found by interpolating the reference height table for your sex between the two bracketing ages.
Percentile: a z-score is computed from the median and standard deviation for your age and sex, then converted to a percentile using the normal distribution.
BMI-for-age: if you enter a weight, BMI is calculated and flagged against healthy ranges so a height result is never read in isolation.

Everything runs locally in your browser. No height, weight or birth date ever leaves your device, and the tool stores nothing between visits.

❓ Height Age FAQ

How accurate is this height age calculator?

It compares your measured standing height against published median heights from CDC and WHO growth reference charts for ages 2 to 20. Because individual growth timing varies widely and genetics differ, treat the result as a percentile estimate rather than a diagnosis: about half of healthy children the same age are shorter than the median and half are taller.

What is a height age and why do doctors use it?

Height age (also called bone-age-adjusted height) is the chronological age at which your height equals the 50th percentile. Pediatric endocrinologists use it together with weight-for-height and mid-parental height to decide whether a child is simply a late bloomer or whether a growth evaluation is warranted.

What is a normal growth rate per year?

Between ages 2 and the start of puberty children normally gain about 5 to 6 cm (2 to 2.4 inches) per year. During the pubertal growth spurt girls peak at roughly 8 to 9 cm per year and boys at 9 to 10 cm per year. A growth rate below 4 cm per year after age 4 is generally worth raising with a pediatrician.

Does adult height depend more on genetics or nutrition?

Twin and family studies put the heritability of adult height at roughly 80 percent, so genetics is the dominant factor. The remaining variation comes from nutrition, sleep, illness and hormones. Mid-parental height gives a realistic target: add the parents' heights and either add 6.5 cm for boys or subtract 6.5 cm for girls, then divide by two, with a normal range of about plus or minus 8.5 cm.

Does this calculator work for adults too?

Yes, but the interpretation changes. After roughly age 20 the growth plates close and adult height is fixed, so the tool reports your height percentile against adult reference data instead of predicting growth. Adults lose about 1 cm of measured height per decade from age 40 onward because of spinal disc compression, which is normal.

When should I see a doctor about a child's height?

Book an evaluation if a child is below the 3rd percentile or above the 97th percentile for age, crosses two or more percentile lines downward on a growth chart, grows less than 4 cm per year after age 4, or enters puberty unusually early or late. A pediatrician can measure bone age from a hand X-ray and check thyroid and growth hormone levels.