ADULT HEIGHT CALCULATOR · CHILD HEIGHT PREDICTOR
How tall will you or your child be?
Estimate adult height for yourself or your child using current measurements and biological parents’ heights.
No child measurements yet? Try the parents-only estimate →
OPTIONAL · EXPERIMENTAL
Add your growth history
Optionally use past heights to adjust your main estimate. Your current measurements, parents’ heights, weight, and selected growth timing still count.
This combined method is experimental. It adds a growth-pattern adjustment of up to 3 cm in either direction to the original formula and your timing scenario. It has not been shown to improve accuracy, and the timing scenario may overlap with information in your history.
Research and limitations
We compare current height and interval growth rates with the Slovenian research histories. The difference in remaining growth between history-matched and current-height-only groups becomes an adjustment to the original estimate, limited to ±3 cm. This is our experimental combination, not the published GCC method. The cap is a design safeguard, not a validated error bound. Reference outcomes end at 18, so they cannot establish true final adult height.
The original formula’s accuracy range does not apply to this combined result. More inputs do not guarantee better accuracy.
Research background ↗Questions about predicting a child’s height
How tall will my child be?
This child height predictor estimates adult height from your child’s age, biological sex, current height and weight, and both biological parents’ heights. Enter your child’s measurements in the first section, then their parents’ heights. The result is an estimate, not a guarantee of how tall your child will grow.
How tall will I be?
Use the same height calculator with your own measurements. The Khamis–Roche equation is used from ages 4 to 17 years 6 months. Under 4, the calculator uses a broad parents-only estimate; above 17 years 6 months, it shows current height as a baseline rather than predicting remaining growth. At 20 and older, your entered height stays unchanged.
Can I add my child’s past height measurements?
Yes. The optional growth-history section supports current ages 8 to 17 years 6 months and at least two past measurements from age 8, spaced 6–24 months apart. You can edit or remove each entry. History adds an experimental adjustment to the main estimate; it has not been shown to improve prediction accuracy.
BEHIND THE NUMBER
Growth, with a little context.
A simple equation. Clear limitations.
Built on the Khamis–Roche method
For ages 4 to 17 years 6 months, we combine current height, weight and the average of both parents’ heights with age- and sex-specific coefficients. We interpolate between half-year reference ages using your entered years and months.
How the calculation works
Adult height = a + b × height + c × weight + d × average parent height
The equation runs in inches and pounds, then converts back to centimetres. We never show an adult estimate or growth timing scenario below your entered current height. The coefficients change with age and sex. Interpolation is an implementation choice, not an independently validated extension of the study.
Below age 4, the fallback is (mother’s height + father’s height ± 13 cm) ÷ 2: add 13 for males, subtract 13 for females. Above 17 years 6 months, we show current height without extrapolating the child equation. At 20 and older, that value stays unchanged.
How accurate is the estimate?
The original model was developed from 433 white American children without growth-affecting conditions. It may be less accurate for other populations or unusual growth patterns. The approximate ranges use average error bounds of ±5.3 cm for males and ±4.3 cm for females; they are not age-specific intervals.
Use measured heights, without shoes. Weight is a statistical input; changing your weight does not cause the predicted change in height. A clinician can assess growth over time and bone age when needed.
What does the growth timing option do?
It is optional, it starts on Average, and on Average it changes nothing at all: the number you get is the plain Khamis–Roche estimate. It is our own addition, not part of the study.
Pick Late bloomer or Early bloomer and we read your height against a maturity 0.6 years younger or older than your actual age, using the same CDC median curve as the chart above. A late maturer has reached less of their adult height than their years suggest, so more of it is still ahead; an early maturer has already spent more of theirs. The difference between those two readings is what we add or subtract.
The idea is borrowed from the Bayley–Pinneau method, which switches between accelerated, average and delayed tables when a bone-age X-ray differs from chronological age by more than a year. We are not doing that. We use a self-description instead of a bone age, and a deliberately smaller shift because of it. The adjustment applies only through puberty, fades to nothing at either end of it, and is capped at 7 cm. Treat it as a what-if, not a second opinion.