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Child Height Predictor

Estimate your child's predicted adult height from mom and dad's height using the mid-parental method — the gold standard in pediatric endocrinology — in feet and inches. Includes a current-height growth projection, the age-2 rule of thumb, and a side-by-side method comparison.

Method Mid-parental Range ±3.3 in Genetic factor 70–80% Updated: Jul 21, 2026
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Pick a typical mother/father height pair, or enter your own height:
Your child's current age and height are compared to an average growth curve (WHO/CDC) to project adult height. Most useful after about age 4 and before puberty.
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Ages 2–17 (e.g. 7.5)
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Rule of thumb: a child's height at age 2 (often 18 months for girls), roughly doubled, gives a rough approximation of adult height. Margin of error is wide.
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Boys: height at 24 months · Girls: height at 18 months.
The Khamis-Roche method adds the child's current weight to age and height, which improves on a plain growth-curve projection because BMI is correlated with skeletal maturity. No X-ray needed. Most reliable ages 4–17.
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Used to estimate skeletal maturity (BMI-adjusted) instead of an X-ray.
Enter parents' height and (optionally) current age/height together; the tool compares the methods side by side and gives a combined estimate:
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⚙️ Display settings
Adult percentile contextShow where the prediction falls relative to the adult average
Method comparisonList other methods' predictions alongside the result
Quick answer A child's predicted adult height is found with the mid-parental method: boy = (mother's height + father's height + 5.1 in) ÷ 2, girl = (mother's height + father's height − 5.1 in) ÷ 2. The result is interpreted with a ±3.3 in target range. About 70–80% of adult height is genetic; the rest is shaped by nutrition, sleep, and hormones.
5'9"Average adult male height
5'4"Average adult female height
70–80%Genetic share of height
±3.3 inMid-parental confidence range
ℹ️ This tool is for informational purposes only and is not a substitute for medical advice. Height predictions show a child's genetic potential, not a guaranteed outcome. Actual height varies within the target range depending on nutrition, sleep, chronic illness, and the timing of puberty. If you have concerns about your child's growth (very short/tall for age, slowing growth), please see a pediatric endocrinologist; a bone-age X-ray gives a more precise estimate.
↕ Child Height Predictor — ToolPico ↗

What is a child height predictor, and how does it work?

The mid-parental (Tanner-Whitehouse) method from parents' height, a current-height growth projection, and the age-2 rule — a full explanation of when each one is most accurate.

A child height predictor estimates the predicted adult height a child is likely to reach. The most common and scientifically grounded approach is the mid-parental method, based on the mother's and father's height. It was first described in 1962 by James Tanner and Reginald Whitehouse and is considered the gold standard in pediatric endocrinology, because roughly 70–80% of adult height is genetic — parents' height is a strong signal for a child's genetic height potential.

How do you calculate a child's height from the parents' height?

Quick answerThe mid-parental formula differs by sex: for a boy, (mother's height + father's height + 5.1 in) ÷ 2; for a girl, (mother's height + father's height − 5.1 in) ÷ 2. Add and subtract about ±3.3 in from that figure to get the normal target range the child will most likely (≈95%) fall within.
  • The ±5.1 in adjustment — applied because adult men average about 5.1 in (13 cm) taller than adult women (some sources express it as ±2.6 in added to the average instead; the result is the same).
  • The ±3.3 in target range — the prediction is not a single number but a range, representing roughly 95% confidence.
  • Mid-parent height — the average of the mother's and father's height, representing the family's genetic height "center."

Predicting adult height from current height

Quick answerA child's current age and height are compared against the median for that age on an average growth curve (WHO/CDC); that ratio is then scaled against the adult median to project adult height. A child who is tall for their age tends to stay tall as an adult, and vice versa. This method is especially useful after about age 4 and before puberty.

The "From current height" tab projects a child's current growth trajectory forward. It assumes the child stays on roughly the same growth channel (percentile band) they're currently on. Early or late puberty can shift this projection, so it's best interpreted alongside the parents'-height prediction.

The age-2-times-2 rule of thumb

Quick answerA well-known rule of thumb says a child's height at age 2 (18 months for girls), roughly doubled, gives a rough approximation of adult height. For example, a boy who is 2 ft 11 in at age 2 has a predicted adult height of roughly 5 ft 10 in. It's simple but has a wide margin of error — use it alongside other methods, not alone.

What affects a child's height? (genetics + environment)

Quick answerAdult height is about 70–80% genetic; the remaining 20–30% is shaped by environment. The most influential environmental factors are balanced nutrition (protein, calcium, vitamin D), sufficient quality sleep (growth hormone is released during deep sleep), physical activity, and the absence of chronic illness. Early/late puberty and hormonal issues also affect final height.

Example: child height by parents' height (mid-parental)

Predicted adult height for different mother/father height pairs. Use the calculator above for your exact figures and target range.

Mid-parental prediction (boy: (M+F+5.1in)/2 · girl: (M+F-5.1in)/2)
MotherFatherBoyGirl
5'1"5'7"5'7"5'1"
5'2"5'8"5'8"5'2"
5'4"5'9"5'9"5'4"
5'4"5'10"5'10"5'4"
5'5"5'11"5'11"5'5"
5'6"6'0"6'0"5'6"
5'7"6'1"6'1"5'7"

Popular calculations

Reference tables & growth data

Citable, evergreen growth references: average height by age (WHO/CDC median), typical annual growth rate, and adult height percentile context — expressed in feet and inches.

Average (median, 50th percentile) height by age
AgeBoysGirls

Source: WHO / CDC growth references (median), converted to feet and inches. Values are approximate and can vary a few inches by population; growth standards don't change year to year (evergreen).

Typical annual height gain by age range
Age rangeAnnual gain
Birth–1 year~9.8 in
1–2 years~4.7 in
2–4 years~3.1 in
4 years–puberty~2.0–2.4 in
Puberty growth spurt~3.1–4.7 in / yr
After puberty≈ 0 (growth stops)

Growth spurts typically peak around age 10–12 in girls and 12–14 in boys. Growth is usually complete by 15–16 in girls and 17–18 in boys.

Adult height percentile context (approximate, U.S. adults)
PercentileMaleFemale
3rd percentile (short)5'4"4'11"
15th percentile5'7"5'2"
50th percentile (average)5'9"5'4"
85th percentile6'0"5'6"
97th percentile (tall)6'2"5'8"

Approximate figures (assuming a normal distribution around the mean). See where your predicted height falls in this table to interpret "short / average / tall" context.

Add this calculator to your site (embed code)

Embed the child height predictor on your own website for free. Copy the code below into your HTML — the tool runs in a simplified view and links back to this page as its source.

The embedded tool has a fixed layout; you can adjust the height value to fit your site. No ads or personal data, runs entirely client-side.

Height & growth terms glossary

Short definitions of the core terms used in child height prediction.

Mid-parental heightThe predicted height calculated from mother and father's height, adjusted by sex; an indicator of genetic height potential.
Target height rangeThe range a child is likely to reach, found by adding/subtracting about 3.3 in from the mid-parental prediction.
Genetic potentialThe height limits a child's family genetics allow. Accounts for roughly 70–80% of adult height.
PercentileA child's (or adult's) rank in height among their peers. The 50th percentile is average; the 3rd is the "short" cutoff.
Bone ageSkeletal maturity determined by a hand/wrist X-ray. A more precise measure than calendar age for predicting height.
Growth spurtThe period of rapid height gain during puberty (about 3–5 in per year).
WHO/CDC growth curveInternational reference charts showing the distribution of children's height and weight by age.
Tanner-WhitehouseThe 1962 reference work that defined the mid-parental method and standard growth stages, still used today.

In-depth guides

Detailed answers to the questions parents ask most about their child's height.

Is my child short for their age? When should I see a doctor?

A child's height should be evaluated if it falls below the 3rd percentile for their peers, or if their growth rate has clearly slowed (dropping across percentile bands on a growth chart). A trend over time matters more than any single measurement.

If a child is well below the target range calculated from parents' height, is growing less than about 1.6 in per year, or is noticeably shorter than peers, it's worth seeing a pediatric endocrinologist. A specialist can investigate the cause with a bone-age X-ray and other relevant tests.

How does early or late puberty affect final height?

Early puberty brings the growth spurt forward; a child may look tall relative to peers for a while, but because growth plates can close earlier, final height can end up shorter than expected. In late puberty, a child may stay shorter for a period, but because growth continues longer, they usually reach their target height.

This is why predictions based on calendar age can be skewed by the timing of puberty. Bone age is the most reliable measure for reducing this uncertainty. If you're concerned about the timing of puberty, a specialist evaluation is important.

How much do nutrition, sleep, and exercise affect height?

Even though height is 70–80% genetic, the remaining 20–30% is environmental and manageable. A balanced diet with enough protein, calcium, and vitamin D supports bone and muscle development. Sleep is critical: most growth hormone is released during deep sleep, so consistent, sufficient sleep matters.

Regular physical activity (especially jumping/hanging-type sports) supports bone health and posture. Treating chronic illness and avoiding secondhand smoke also support healthy growth. These factors help a child reach the upper end of their genetic potential, but they can't push height far beyond that ceiling.

Frequently asked questions

How tall will my child be?
Your child's predicted adult height is estimated from parents' height using the mid-parental method: boy = (mother's height + father's height + 5.1 in) ÷ 2, girl = (mother's height + father's height − 5.1 in) ÷ 2. The result is interpreted with a ±3.3 in range. For example, if the mother is 5'4" and the father is 5'10", a boy's predicted height is about 5'10" (roughly 5'6"–6'1"). Use the calculator above for your exact numbers.
How do you calculate a child's height from the parents' height?
Add the mother's and father's height together. For a boy, add about 5.1 in to that sum and divide by 2; for a girl, subtract about 5.1 in from the sum and divide by 2. This is the mid-parental (mid-parent) method and gives the child's genetic height potential. A ±3.3 in target range is then applied for precision.
What is the mid-parental method?
The mid-parental (mid-parent) method is a height-prediction method described by Tanner and Whitehouse in 1962 and considered the gold standard in pediatric endocrinology. It applies a sex-specific adjustment to the average of the mother's and father's height to calculate the child's genetic height potential. Confidence range is ±3.3 in (≈95% confidence).
How do you predict a girl's adult height?
A girl's predicted adult height is found with (mother's height + father's height − 5.1 in) ÷ 2. For example, if the mother is 5'4" and the father is 5'10", the prediction is about 5'4" (roughly 5'1"–5'8"). Because puberty tends to start earlier in girls, growth is usually mostly complete by age 15–16.
Is doubling a child's age-2 height accurate?
This is a rule of thumb: a child's height at age 2 (24 months for boys, often 18 months for girls), roughly doubled, approximates adult height. It gives an easy estimate but the margin of error is wide (±3 in or more). The mid-parental method based on parents' height is generally more reliable; the best approach weighs several methods together.
What affects a child's height?
Adult height is about 70–80% genetic. The rest is shaped by environment: balanced nutrition (protein, calcium, vitamin D), quality and sufficient sleep (growth hormone is released during deep sleep), regular physical activity, and the absence of chronic illness. Early/late puberty and hormonal conditions also affect final height.
How is height predicted? Which method is most accurate?
There are three practical methods: (1) the mid-parental method based on parents' height; (2) a current-height projection that compares a child's age and height to a growth curve; (3) the age-2-times-2 rule. Mid-parental is the most reliable single method; for the best estimate, weigh several together (the "Compare" tab does this). The clinically most precise method is a bone-age-based prediction, which requires a doctor's evaluation.
How accurate are height predictions? Where does the data come from?
No height prediction is exact; predictions show genetic potential. The mid-parental confidence range is ±3.3 in. This tool uses the Tanner-Whitehouse mid-parental formula and WHO/CDC growth references; these standards are evergreen (they don't change year to year). For medical concerns, see a pediatric endocrinologist. Last updated: July 21, 2026.
What's the difference between the mid-parental method and a current-height projection?
The mid-parental method uses only parents' height and works from birth onward. The current-height projection compares a child's present age and height to an average growth curve, scaling the ratio to the adult average — most useful after about age 4 and before puberty. Using both together (the "Compare" tab) gives a fuller picture than either alone.
What is the Khamis-Roche method?
The Khamis-Roche method (1994) predicts adult height from a child's current stature, weight, age, and sex — no bone-age X-ray required. Weight is used (via BMI) as a stand-in for skeletal maturity: a higher BMI-for-age suggests the child is closer to their final height already, while a lower BMI-for-age suggests more growth remaining. It's generally used from about age 4 to 17 and is available here as the "Khamis-Roche" tab.

Methodology & sources

ToolPico's Child Height Predictor is a free, independent tool. The calculation engine directly implements three scientific/practical methods: the mid-parental (Tanner-Whitehouse, 1962) formula — boy (mother+father+5.1in)/2, girl (mother+father−5.1in)/2, with a ±3.3 in target range; a proportional projection from current height — the child's ratio to the median height for their age is scaled to the adult median using the WHO/CDC reference curve; and the age-2-times-2 rule. Adult percentile context is calculated from a normal-distribution assumption (mean ± standard deviation). All height figures are entered and displayed in feet and inches by default.

Sources: Tanner JM, Whitehouse RH (1962) mid-parental method · World Health Organization (WHO) child growth standards · U.S. Centers for Disease Control and Prevention (CDC) growth reference data. All calculations run in the browser (client-side); no data is sent to a server. Last updated: July 21, 2026. Results are for informational purposes only and do not constitute medical advice.

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