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How tall will your kids be?

Last updated: 3 July 2026

Four prediction methods, side by side. Parent heights get you a rough range. Add your child's current height, weight, and age and the prediction tightens dramatically. None of these replace a paediatrician with an X-ray, but for the playground question of "will my kid be taller than me", they're more honest than any single calculator.

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Please enter sex and both parents' heights to predict.
Predicted range across all methods
How confident should you be? Predictions for children under 4 are essentially a coin flip. After puberty, methods using current height + weight (Khamis-Roche) typically land within 4 to 5 cm of the actual adult height. Mid-parental height alone has a 95% confidence interval of roughly 10 cm either side. The only method that gets to 2 cm is a bone-age X-ray, which your paediatrician can order if you actually need precision.

The four methods, explained

1. Mid-parental height (everyone has the data)

The classic. Take the average of mum and dad's height, then add 6.5 cm for a boy or subtract 6.5 cm for a girl. The 6.5 cm adjustment is the population-average difference in adult male and female height. It's the only method that works when you have no information about your child yet, but the 95% confidence interval is plus or minus 10 cm. That's a real 20 cm spread, which is why the same parents can produce a 175 cm son and a 195 cm son.

2. Khamis-Roche (the gold standard for online prediction)

Developed in 1994 using the Fels Longitudinal Study, this method combines your child's current height, weight and age with the mid-parental height. The confidence interval drops to roughly plus or minus 4 to 5 cm for children over 4 years old. It's what most paediatric calculators use under the hood. Our version is a faithful approximation: it weights your child's current measurements against the parent average and adjusts for sex and age, without the full age-stratified coefficient tables a clinic would use.

3. Double the height at age 2 (the folk wisdom one)

An old paediatric rule of thumb: a child's height at age 2 (boys) or 18 months (girls) is roughly half their adult height. The plus or minus is still around 10 cm, so it's no better than mid-parental for accuracy, but parents remember the toddler check-up height and the method is satisfyingly simple. If you don't remember the exact age-2 height, this method gets less reliable fast.

4. Current-height multiplier (works at any age)

For children aged 4 to 12, you can multiply current height by an age- and sex-specific factor to project forward. Less precise than Khamis-Roche but more forgiving on data quality: even an estimated age and a rough current height get you a sensible range. We use the CDC growth chart percentile multipliers.

Average heights by country, for context

Data from large-scale national health surveys. Australia sits comfortably in the middle of the pack, with the average bloke at 178.4 cm (5 ft 10.2 in) and the average woman at 164.6 cm (5 ft 4.8 in).

CountryMaleFemale
🇳🇱 Netherlands183.8 cm (6 ft 0.4 in)170.4 cm (5 ft 7.1 in)
🇩🇰 Denmark182.5 cm (5 ft 11.9 in)169.3 cm (5 ft 6.7 in)
🇸🇪 Sweden182.3 cm (5 ft 11.8 in)168.7 cm (5 ft 6.4 in)
🇳🇴 Norway182.1 cm (5 ft 11.7 in)168.4 cm (5 ft 6.3 in)
🇩🇪 Germany181.7 cm (5 ft 11.5 in)167.8 cm (5 ft 6.1 in)
🇦🇺 Australia178.4 cm (5 ft 10.2 in)164.6 cm (5 ft 4.8 in)
🇨🇦 Canada178.1 cm (5 ft 10.1 in)164.3 cm (5 ft 4.7 in)
🇳🇿 New Zealand177.8 cm (5 ft 10.0 in)164.1 cm (5 ft 4.6 in)
🇺🇸 USA177.1 cm (5 ft 9.7 in)163.5 cm (5 ft 4.4 in)
🇬🇧 UK177.5 cm (5 ft 9.9 in)164.4 cm (5 ft 4.7 in)
🇫🇷 France176.8 cm (5 ft 9.6 in)163.2 cm (5 ft 4.3 in)
🇧🇷 Brazil175.5 cm (5 ft 9.1 in)162.1 cm (5 ft 3.8 in)
🇲🇽 Mexico169.8 cm (5 ft 6.9 in)158.7 cm (5 ft 2.5 in)
🇨🇳 China171.8 cm (5 ft 7.6 in)159.7 cm (5 ft 2.9 in)
🇰🇷 South Korea175.2 cm (5 ft 9.0 in)162.3 cm (5 ft 3.9 in)
🇯🇵 Japan170.8 cm (5 ft 7.2 in)158.0 cm (5 ft 2.2 in)
🇿🇦 South Africa172.6 cm (5 ft 8.0 in)160.8 cm (5 ft 3.3 in)
🇮🇳 India166.5 cm (5 ft 5.6 in)155.2 cm (5 ft 1.1 in)
🇵🇭 Philippines163.2 cm (5 ft 4.3 in)152.1 cm (4 ft 11.9 in)
🇮🇩 Indonesia165.8 cm (5 ft 5.3 in)154.5 cm (5 ft 0.8 in)
Height Predictor FAQ
Which of the four methods should I trust?
If you have your child's current height, weight and age, trust Khamis-Roche. It's the tightest method here, usually within 4 to 5 cm for kids over four. With only the two parent heights you're left with mid-parental, which is honest but loose (plus or minus 10 cm). The doubling rule and the current-height multiplier are sanity checks, not the headline. The best-guess number up top is a weighted average that leans on Khamis-Roche whenever it has the data.
Why show four methods instead of one?
Because no single height-prediction method is honest on its own. Mid-parental works for everyone but is loose. Khamis-Roche is tight but needs current measurements. The doubling rule only works near age two. Putting them side by side shows you the real spread and stops any one method pretending to be gospel.
What if one parent is much taller than the other?
The methods average the two parent heights, so a big gap just lands the prediction in the middle. If you're 1.85 metres and your partner is 1.60 metres, the parent average is 1.725 metres and mid-parental works off that. The real spread is wider than the average suggests, which is why mid-parental carries a plus or minus 10 cm range. Add your child's current height, weight and age and Khamis-Roche tightens that to about 4 to 5 cm.
Does this work for kids who are adopted or from blended families?
Mid-parental and the doubling rule lean on biological parent heights, so they need accurate biological figures to mean anything. If you don't have those, the Khamis-Roche and current-height multiplier methods are more useful once the child is old enough to measure, because they read the child's own growth rather than the parents' genes.
My kid is already off the prediction. Should I worry?
Probably not. Even the tight methods carry a few centimetres of range, and mid-parental carries ten. One measurement doesn't mean much. What matters is the trend: a child tracking steadily along their own growth percentile is fine. A sudden drop across percentiles is the thing worth raising with your GP or paediatrician.
Can nutrition change how tall my kid grows?
Yes. Serious, long-term malnutrition stunts growth and can do so permanently. But for a child eating a decent, varied diet, food isn't the lever that pushes them past their genetic potential. Good nutrition lets them reach it; it won't add height beyond what the genes allow.
What age should I stop using this predictor?
The predictions are most useful while there's real growing left to do. Girls usually finish around 16 to 18, boys around 18 to 20. Once the growth plates fuse, current height is close to the final answer and the methods add little. That's why Khamis-Roche and the multiplier method only run between ages 4 and 17.
Is any of this medical advice?
No. It's an informational tool. The only method that gets you to within about 2 cm is a bone-age X-ray, which a paediatrician can order if there's a real reason to. If you're worried about your child's growth, see your GP.
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Sources and verification

Height prediction formulas come from Tanner et al. (1970) for the mid-parental method, Khamis and Roche (1994) using the Fels Longitudinal Study for the multi-input method, the World Health Organization Growth Reference for the doubling method, and CDC age-specific growth charts for the multiplier method. Average height data comes from the NCD Risk Factor Collaboration, which pools data from over 2,000 population-based studies. Australian figures are cross-referenced with the Australian Bureau of Statistics National Health Survey 2022. Celebrity height data sources: official biography measurements where verifiable, IMDb otherwise. This calculator is for informational purposes only and is not medical advice.