📏 Child Height Predictor: How Tall Will My Child Be?
By Shihab Mia · Updated 2026-06-30
This child height predictor is a rough estimate based on parental height only and is not medical advice. The mid-parental method has a wide margin of about plus or minus 8.5 cm (3.3 inches), and a child's real adult height also depends on nutrition, overall health, hormones, genetics beyond the parents, and the timing of puberty. If you have any concern about how your child is growing, speak to a paediatrician or use proper clinical growth charts.
This child height predictor estimates how tall your child will be as an adult using the mid-parental height method, the quick check doctors often use. For a boy, add the parents' heights plus 13 cm and divide by two; for a girl, add the parents' heights minus 13 cm and divide by two. The result is the centre of a likely range of about plus or minus 8.5 cm. So if you predict 176 cm, your child will most likely finish somewhere between roughly 168 cm and 185 cm. Choose the child's sex, enter the mother's and father's heights in cm or feet, and you get the prediction and range instantly. Because it is based on the parents and not the child's current size, the same child height predictor works for a baby, a toddler, or a teenager.
What is the Child Height Predictor?
The mid-parental method behind this child height predictor estimates a child's adult height from the average of the two parents' heights, adjusted for the child's sex. Height is strongly inherited, so a child tends to land near the genetic midpoint of their parents. Because adult men are on average about 13 cm (roughly 5 inches) taller than adult women, the formula adds 13 cm for a boy and subtracts 13 cm for a girl. The single figure it produces is sometimes called the target height or genetic height, and it represents the centre of where the child is genetically aimed.
The key thing to understand is that the number is the middle of a range, not a guarantee. Real adult heights for children with the same parents scatter around that midpoint. The commonly cited margin of plus or minus 8.5 cm is roughly one standard deviation, meaning about two thirds of children finish inside that band and the rest land outside it. So a child height predictor result of 176 cm honestly points to a likely range of about 168 cm to 185 cm. This is why you should always read both the number and the range, never just the single value.
The mid-parental approach is deliberately simple, and it ignores several real factors. Nutrition, general and chronic health, sleep, physical activity, hormone levels, and especially how early or late puberty arrives all shift the final result. Two children with identical parents can differ by several centimetres for these reasons. Improved nutrition across generations is also why many children today end up taller than both of their parents. Treat this child height predictor as a friendly ballpark rather than a precise forecast.
If you want more accuracy, there are more advanced methods. The Khamis-Roche method adds the child's current height and weight to the parental average and is generally more accurate than the mid-parental formula for children aged four and over, with a margin of around plus or minus 5 cm. Bone-age methods such as Bayley-Pinneau read skeletal maturity from a hand X-ray and are more accurate still, especially for children with unusually early or late puberty, but they require a clinical visit. Our child height predictor uses the mid-parental method because it needs only the two parents' heights and no measurements, X-rays, or appointments.
The most useful way to use this child height predictor is alongside your child's growth chart. The predictor tells you the genetic target; the growth chart shows whether your child is actually tracking towards it. A child who is consistently growing far below the predicted band, or whose growth curve suddenly flattens or shoots up, is worth discussing with a doctor. In that sense the tool is not just a curiosity, it is a simple screen for spotting when a child is growing very differently from the family pattern.
Finally, remember the limits. A child height predictor based on parents alone cannot account for medical conditions, growth-hormone issues, or extreme athletic training, all of which can move a child well outside the predicted range. It is a starting point for a conversation, not a diagnosis or a promise.
When to use it
- Satisfying a parent's curiosity about how tall a baby or toddler might grow up to be.
- Getting a quick genetic target height to compare against a child's current growth-chart percentile.
- Helping a teenager understand their likely adult height range during a growth spurt.
- Spotting early when a child is growing far above or below the family height pattern, as a prompt to ask a doctor.
- Estimating long-term sizing needs, for example for sports involvement, beds, or clothing planning.
- Comparing predicted heights for siblings to set realistic expectations across the family.
How to use the Child Height Predictor
- Choose whether the child is a boy or a girl, because the sex adjustment changes the result by 13 cm.
- Pick metric (cm) or imperial (feet and inches) units.
- Enter the mother's height in the units you selected.
- Enter the father's height in the same units.
- Read the predicted adult height and the likely range (about plus or minus 8.5 cm) that appears instantly.
Formula & method
Worked examples
A boy whose mother is 162 cm and father is 178 cm tall.
- Add the parents: 178 + 162 = 340 cm
- Add 13 cm for a boy: 340 + 13 = 353 cm
- Divide by 2: 353 / 2 = 176.5 cm
- Apply the range: 176.5 - 8.5 = 168.0 cm, 176.5 + 8.5 = 185.0 cm
Result: Predicted adult height about 176.5 cm, likely range 168.0 to 185.0 cm.
A girl whose mother is 162 cm and father is 178 cm tall.
- Add the parents: 178 + 162 = 340 cm
- Subtract 13 cm for a girl: 340 - 13 = 327 cm
- Divide by 2: 327 / 2 = 163.5 cm
- Apply the range: 163.5 - 8.5 = 155.0 cm, 163.5 + 8.5 = 172.0 cm
Result: Predicted adult height about 163.5 cm, likely range 155.0 to 172.0 cm.
A boy with imperial heights: mother 5 ft 4 in and father 6 ft 1 in.
- Convert to cm: mother 5 ft 4 in = 162.6 cm, father 6 ft 1 in = 185.4 cm
- Add the parents: 185.4 + 162.6 = 348.0 cm
- Add 13 cm for a boy: 348.0 + 13 = 361.0 cm
- Divide by 2: 361.0 / 2 = 180.5 cm (about 5 ft 11 in)
- Apply the range: 180.5 - 8.5 = 172.0 cm, 180.5 + 8.5 = 189.0 cm
Result: Predicted adult height about 180.5 cm (5 ft 11 in), likely range 172.0 to 189.0 cm.
Predicted adult height by parents (mid-parental method, midpoint values)
| Mother | Father | Boy prediction | Girl prediction |
|---|---|---|---|
| 155 cm | 170 cm | 169.0 cm | 156.0 cm |
| 160 cm | 175 cm | 174.0 cm | 161.0 cm |
| 165 cm | 180 cm | 179.0 cm | 166.0 cm |
| 170 cm | 185 cm | 184.0 cm | 171.0 cm |
| 175 cm | 190 cm | 189.0 cm | 176.0 cm |
How prediction methods compare on accuracy
| Method | What it needs | Typical margin |
|---|---|---|
| Mid-parental (this tool) | Both parents heights only | About plus or minus 8.5 cm |
| Khamis-Roche | Child height, weight, parent average | About plus or minus 5 cm (age 4+) |
| Bone age (Bayley-Pinneau) | Hand X-ray plus current height | About plus or minus 2.5 cm |
Quick height conversion reference
| Centimetres | Feet and inches |
|---|---|
| 155 cm | 5 ft 1 in |
| 165 cm | 5 ft 5 in |
| 175 cm | 5 ft 9 in |
| 185 cm | 6 ft 1 in |
| 195 cm | 6 ft 5 in |
Common mistakes to avoid
- Treating the number as exact. The prediction is the centre of a wide range, about plus or minus 8.5 cm. A child can comfortably finish several centimetres above or below the figure, so read it as a ballpark, not a promise.
- Swapping the boy and girl adjustment. You add 13 cm for a boy and subtract 13 cm for a girl. Mixing these up shifts the estimate by 13 cm in the wrong direction, so always select the correct sex first.
- Mixing up units. Entering one parent in centimetres and the other in inches gives a nonsense result. Pick metric or imperial and enter both parents the same way.
- Ignoring health and puberty timing. The formula uses parents only. Nutrition, chronic illness, hormones, and early or late puberty can move a child well outside the predicted range, so it is no substitute for a growth check by a doctor.
- Expecting it to spot a medical problem. A child height predictor cannot detect growth-hormone issues or other conditions. If a child is far off the family pattern or their growth curve changes sharply, that needs a clinical assessment, not a calculator.
- Using a rounded or guessed parent height. Each centimetre of parent error feeds straight into the result. Measure both parents properly without shoes rather than guessing, so the prediction starts from accurate numbers.
Glossary
- Mid-parental height
- The estimate of a child's adult height based on the average of the two parents' heights, adjusted for sex. Also called target or genetic height.
- Target height
- Another name for the mid-parental estimate, the height a child is genetically aimed at reaching as an adult.
- Prediction interval
- The range around the estimate within which most children actually finish, here about plus or minus 8.5 cm (roughly one standard deviation).
- Growth chart
- A medical chart that plots a child's height and weight against age-based percentiles to track growth over time.
- Percentile
- A ranking that shows how a child compares with peers, for example the 50th percentile is the median height for that age.
- Khamis-Roche method
- A more accurate prediction method that adds the child's current height and weight to the parental average, without needing an X-ray.
- Bone age
- Skeletal maturity read from a hand X-ray, used by clinical methods such as Bayley-Pinneau to make a more precise height prediction.
- Standard deviation
- A measure of spread. About two thirds of values fall within one standard deviation of the average, which is why the plus or minus 8.5 cm band is not a hard limit.
Frequently asked questions
How accurate is the mid-parental height method?
The mid-parental method is a useful rough guide, not a precise forecast. Its margin is about plus or minus 8.5 cm (around 3.3 inches), which is roughly one standard deviation, so about two thirds of children finish within that band around the estimate. Individual results vary with nutrition, health, and the timing of puberty. For more accuracy, the Khamis-Roche method narrows the margin to about plus or minus 5 cm.
How tall will my child be?
To predict how tall your child will be, take the average of both parents' heights and adjust for sex: add 13 cm for a boy or subtract 13 cm for a girl, then divide by two. For example, with a mother of 162 cm and father of 178 cm, a boy is predicted at about 176.5 cm and a girl at about 163.5 cm. Treat the result as the centre of a range of about plus or minus 8.5 cm.
What is the formula to predict a child height?
The mid-parental formula is: for a boy, predicted height equals (father height plus mother height plus 13 cm) divided by two; for a girl, it equals (father height plus mother height minus 13 cm) divided by two. The 13 cm reflects the average difference between adult men and women. The final answer is the middle of a likely range of plus or minus 8.5 cm.
Why does the formula add or subtract 13 cm?
On average adult men are about 13 cm (roughly 5 inches) taller than adult women. The mid-parental formula shifts the parental average up by 13 cm for a boy and down by 13 cm for a girl to reflect that typical difference between the sexes, so the prediction lands in the right place for the child.
Can a child grow taller than both parents?
Yes, a child can grow taller than both parents. The real range spans about plus or minus 8.5 cm around the estimate, so a child can land above the parental midpoint by chance. Better nutrition and health across generations also push final heights up, which is why many children today end up taller than either parent. The reverse can also happen.
Does a child height predictor work for a baby or toddler?
Yes. The mid-parental method is based only on the parents, not the child's current size, so it works at any age, including for a baby or toddler. For young children a doctor may instead track growth-chart percentiles, which use the child's own measurements over time to see whether growth is on track.
What else affects how tall a child becomes?
Beyond the parents, final height depends on nutrition, general and chronic health, hormones, sleep, physical activity, and especially the timing of puberty. Genetics from earlier generations also plays a part. Because the formula ignores all of these, two children with identical parents can still differ by several centimetres.
What is the most accurate way to predict a child height?
The most accurate prediction comes from a bone-age method such as Bayley-Pinneau, which reads skeletal maturity from a hand X-ray and has a margin of about plus or minus 2.5 cm, but it needs a clinical visit. The Khamis-Roche method (height, weight, and parent average) is the most accurate no-X-ray option at around plus or minus 5 cm. The mid-parental method used here is the simplest and needs only the parents.
At what age does the prediction become more reliable?
Predictions become more reliable as a child gets older, with the best results after about age eight, because more of the growth pattern and puberty timing is known. The mid-parental estimate itself does not change with age since it uses only the parents, but comparing it against a growth chart becomes more informative as the child grows.
Is this child height predictor medical advice?
No. This child height predictor is for general information and curiosity only, and it is not medical advice. It cannot detect growth-hormone problems or other conditions. If your child is growing far above or below the family pattern, or their growth curve changes sharply, speak to a paediatrician for a proper assessment.
Sources
- Predicting a child's adult height , Nemours KidsHealth
- Predicting adult stature from mid-parental height (target height) , U.S. National Library of Medicine (PubMed)
- Growth charts and child growth assessment , U.S. Centers for Disease Control and Prevention (CDC)