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How tall will your kids be?

Last updated: 11 April 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 uses your child's current height, weight, age, and mid-parental height together. 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 implementation uses the published coefficient tables and adjusts for both sex and age in half-year increments.

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
What if one parent is much taller than the other?
The formula averages them out. If you're 1.85 metres and your partner is 1.60 metres, the average is 1.725 metres. The child could be taller, shorter, or right in the middle depending on which genes they inherit. That's why the plus or minus 8.5 centimetre margin of error matters: it accounts for that variation.
Does this work for kids who are adopted or from blended families?
This tool uses biological parent heights because height is mostly inherited. If you don't have accurate biological parent heights, the estimate won't be reliable. For adopted kids, you might find the Khamis-Roche method more useful once the child is old enough to measure reliably, since it focuses on the child's current growth pattern rather than genes.
My kid is way off the prediction already. Should I worry?
Not necessarily. Remember the plus or minus 8.5 centimetre range. If your eight year old is sitting on the low end of that range but tracking their own growth percentile consistently, they're fine. If they've suddenly dropped percentiles or slowed dramatically, that's worth mentioning to your GP or paediatrician. One measurement doesn't mean much. Trends matter.
Can nutrition change how tall my kid grows?
Yes, seriously. Severe malnutrition stunts growth, sometimes permanently. But if your kid has decent food, they'll probably reach their genetic potential. Milk, protein, fruits and veg all help, but you don't need anything fancy. Bad nutrition can make a kid shorter than the prediction. Good nutrition won't make them taller than their genes allow.
What age should I stop using this predictor?
The formula works best for children who aren't done growing yet. Once a kid hits their late teens (girls usually stop growing by 16 to 18, boys by 18 to 20), they're close to final height anyway. Plugging in your heights when your kid is 17 doesn't add much value. Growth plates fusing is the real signal that growth is done.
Is the plus or minus 8.5 centimetre range the same for every kid?
It's an average range. Some kids will land closer to the prediction, some further away. The range captures about two thirds of healthy kids. That means one third will still fall outside it, which sounds high until you remember that genetics is messy and environmental factors matter too.
Should I use this if parents have very different ethnic backgrounds?
The formula works across all populations, but the underlying data comes mostly from Western cohorts. If you want a more precise estimate, the Khamis-Roche method might be better once your child is old enough to measure. Either way, the prediction is still a useful ballpark.
Can I predict height if one parent is unusually tall or short?
You can run the numbers, but the prediction becomes less reliable. If you're unusually tall or short compared to your family background, your kid might regress toward the average somewhat. This is called regression to the mean. A very tall parent with average partner height might have kids who are tall but not as tall as the parent. The plus or minus margin widens in these cases.
Related Converters
Feet to Centimetres Centimetres to Feet Inches to Centimetres Kilograms to Pounds

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.