Child Adult Height Predictor
How tall might your child be? A family target range and a growth-chart projection.
Enter both parents’ heights.
Height-for-age chart
CDC 2000 stature-for-age curves (3rd, 50th and 97th percentiles), ages 2 to 20.
How it was calculated
For general information only, not medical advice. Consult a qualified health professional for advice about your situation.
About the Child Adult Height Predictor
Children tend to grow towards a height set largely by their parents. Paediatricians estimate it with the mid-parental target height: the average of the parents’ heights, adjusted for the child’s sex, with a range of ± 8.5 cm around it (Tanner, 1970).
This calculator gives that family target and its range, and — if you add your child’s age and current height — a second estimate: where your child would end up at 20 if they stayed on their current percentile of the CDC height-for-age chart. Comparing the two is what doctors do; both are shown on a growth chart. It is an estimate for curiosity and conversation with your doctor, not a guarantee.
How to use it
- Choose girl or boy and enter the mother’s and father’s heights (cm, or feet and inches). Measured heights are better than remembered ones.
- Read the target adult height and its likely range.
- Optionally add your child’s age (years and months, or date of birth) and current standing height to see their height percentile now and the projected adult height.
- Check whether the projection falls inside the family range, and use Copy result to keep a note.
Examples
Target (175 + 160 − 13) ÷ 2 = 161 cm · likely range 152.5–169.5 cm
Target (175 + 160 + 13) ÷ 2 = 174 cm · likely range 165.5–182.5 cm
46th percentile now on the CDC chart · projects to about 162.7 cm at 20 — inside the family range
Target about 176.7 cm (5 ft 9.6 in) · range 168.2–185.2 cm
The mid-parental method
Tanner’s formula takes 13 cm as the average difference between the heights of men and women, and converts one parent’s height to the child’s sex before averaging:
- Boys: (father + mother + 13 cm) ÷ 2
- Girls: (father + mother − 13 cm) ÷ 2
Tanner and colleagues estimated that a child’s adult height should fall within ± 8.5 cm of this target, roughly the 3rd to 97th centiles; they later widened it to ± 9 cm for girls and ± 10 cm for boys. Researchers have proposed other constants for other populations — including Japan, Taiwan and India — to allow for the fact that each generation tends to be taller, but none has replaced Tanner’s formula in everyday use.
The growth-chart projection
The calculator finds your child’s z-score (and percentile) on the CDC 2000 stature-for-age chart for their exact age and sex, then reads off the height at 20 years for the same z-score. Clinicians compare this “projected height” with the target: a large difference can be a reason to look more closely at a child’s growth. Children often move a little up or down the percentiles, particularly around puberty, so a single projection is only a rough guide. The CDC chart is a US reference; Indian Academy of Pediatrics charts are recommended for Indian children aged 5–18 and may give a different percentile.
Why there is no Khamis–Roche prediction here
The Khamis–Roche method (1994) predicts adult height from a child’s height, weight and the parents’ heights with age-specific coefficients. Its authors limited its use to white American children without conditions affecting growth — it was built from 223 boys and 210 girls in the Fels Longitudinal Study in Ohio — and its coefficient tables were corrected in a 1995 erratum that is not freely available. We only include methods we can check against their published sources, so this calculator does not offer it.
When to talk to a doctor
Height is checked over time, not from one measurement. Ask your child’s doctor if their height is below the 3rd percentile (the conventional lower limit of normal), if it moves noticeably across percentile lines between measurements, or if the projection from the chart is well outside the family range.
Sources
- Tanner JM, Goldstein H, Whitehouse RH. Standards for children’s height at ages 2–9 years allowing for heights of parents. Arch Dis Child 1970;45:755-62
- Ciancia S, Ribes Cajas P, Cools M. How accurate is Tanner’s formula in estimating target height? BMC Pediatr 2026;26:30 — the formula, the ± 8.5 cm range and later population-specific versions
- Zeevi D et al. Accurate prediction of children’s target height from their mid-parental height. Children (Basel) 2024;11:916 — the range as 3rd–97th centiles, its later revision and projected height
- CDC. Stature-for-age LMS data file (CDC 2000 growth charts)
- Khamis HJ, Roche AF. Predicting adult stature without using skeletal age: the Khamis-Roche method. Pediatrics 1994;94:504-7 (erratum Pediatrics 1995;95:457)
Limitations
- Both methods are estimates: genes, nutrition, health and the timing of puberty all affect final height.
- Not for children with medical conditions that affect growth, except with a doctor’s advice.
- The projection uses the CDC charts (US children) for ages 2 to 19; the family target works at any age.
- Parent heights of 120–230 cm and child heights of 60–230 cm are accepted.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
How accurate is the mid-parental height?
It gives a range, not a number: Tanner expected most children (about the 3rd to 97th centile) to end within 8.5 cm of the target. Treat the middle of the range as a guide, not a forecast.
Why add 13 cm for boys and subtract it for girls?
Tanner used 13 cm as the average difference between adult men and women. Adding it to the mother’s height (for a boy) or subtracting it from the father’s (for a girl) puts both parents on the same scale before averaging. The real difference varies between populations — a review lists 13.9 cm for Italy, 14.4 cm for Flanders and 15.8 cm for India — which is one reason other formulas exist.
My child is much taller or shorter than the target. Should I worry?
Not necessarily. The range was set to cover roughly the 3rd to 97th centiles, so by design a few children in every hundred end up outside it. Doctors look at growth over time: steady growth along a percentile is reassuring, while dropping or rising across percentiles is worth checking.
Does the growth chart projection work for Indian children?
It uses the US CDC charts. The Indian Academy of Pediatrics recommends its own 2015 charts for children aged 5 to 18, so your child may sit on a different percentile there. The family target does not depend on any chart.
Why is there no prediction from weight or bone age?
Methods that use bone age need an X-ray read by a specialist. The Khamis–Roche method uses weight but was developed only in white American children and its coefficient tables are not openly published, so we do not include it.