Adult Height from Childhood Calculator: Predict Adult Height from a Child’s Height and Age
Estimate how tall a child will be as an adult from their current height, age and sex, using the percent-of-adult-height method and the CDC growth-chart percentile, with the current percentile, a rough range, a height-by-age path and an optional mid-parental check.
How it works
Percent method: adult height = current height ÷ (percent of adult height reached at this age ÷ 100) · Growth-chart method: z = ((height ÷ M)^L − 1) ÷ (L × S) at the current age, adult height = M₂₀ × (1 + L₂₀ × S₂₀ × z)^(1/L₂₀) · Mid-parental check: boy (mother + father + 13 cm) ÷ 2, girl (mother + father − 13 cm) ÷ 2
The calculator gives two independent estimates from the child’s own height and age. The percent-of-adult-height method uses reference values for the share of final height a typical child has reached at each age: about 50% for a 2-year-old boy, 53% for a 2-year-old girl, and over 84% (boys) or 92% (girls) by 12. Dividing today’s height by that share projects the adult height. Values between whole years are interpolated, and the table stops at 12 because puberty timing makes it unreliable after that. The growth-chart method finds the child’s z-score on the CDC 2000 stature-for-age chart with the LMS formula and assumes the child stays on the same percentile until 20. Many children do track their percentile from about age 2, but some drift, especially around puberty. Both estimates ignore bone age and the timing of puberty, so read them as a rough guide with a band of about ±6 cm. If you add both parents’ heights under More options, the calculator also shows the mid-parental target (Tanner method, ±8.5 cm). When the methods agree, the prediction is more trustworthy; a big gap is a reason to watch the growth chart. A pediatrician can use a bone-age X-ray for a clinical prediction.
Worked example
A boy aged 3 is 95 cm tall. At 3, boys have reached about 53.8% of adult height, so 95 ÷ 0.538 = 176.6 cm (5′10″), with a rough range of 171–183 cm. On the CDC chart, 95 cm at 3 years is the 51st percentile (z = 0.01); the same z at age 20 gives 177.0 cm. The two methods differ by only 0.4 cm, so the main estimate of about 177 cm is reasonably consistent. He still has about 81.6 cm to grow.
Sources: CDC: 2000 growth charts, stature-for-age LMS data files · Omni Calculator: Height calculator (Khamis-Roche and mid-parental methods) · Inch Calculator: Child height prediction calculator · Calculator.net: Height calculator
Frequently asked questions
How can I predict my child’s adult height from their current height?
Divide the current height by the share of adult height a typical child has reached at that age (for example about 53.8% for a 3-year-old boy), or keep the child on the same growth-chart percentile until age 20. This calculator does both and shows them side by side.
Is it true that a child is half their adult height at age 2?
Roughly. Boys are about 49.5% of adult height at 2 and girls about 52.8%, so doubling a 2-year-old’s height slightly overestimates a girl and slightly underestimates a boy. The doubling rule is a quick guess, not a measurement.
How accurate are these predictions?
For a healthy child growing steadily, most land within about 5–8 cm of the estimate. The timing of puberty, illness and nutrition can shift the final height by more. A bone-age X-ray read by a doctor gives a better prediction, especially after 8–10 years of age.
Why do the two methods give different answers?
They rely on different reference data: one on the average share of adult height reached at each age, the other on the CDC percentile curves. A child who is taller or shorter than average for age can be treated a little differently by each. When they agree, the estimate is more reliable.
How does this differ from the mid-parental method?
The mid-parental method uses only the parents’ heights (the child’s genetic target). This calculator starts from the child’s own growth. You can add both parents’ heights under More options to compare the two.
When should I talk to a doctor about my child’s height?
If the child is below the 3rd or above the 97th percentile, crosses percentile lines on the growth chart, grows less than about 5 cm a year before puberty, or is tracking far below the parents’ target, ask a pediatrician to review the growth chart.
Related calculators
This is a general educational estimate, not medical advice. Every child grows at their own pace. For anything about your child’s growth or health, follow the guidance of your pediatrician.