📐 Height Calculator: Predict Adult Height from Parents
By Shihab Mia · Reviewed by ToolNimba Review Team, Health content reviewed for accuracy · Updated 2026-07-26
This height calculator gives a rough estimate for general information only and is not professional medical advice. For concerns about a child growth, speak with a paediatrician.
Enter both parents' heights and this height calculator predicts the child's likely adult height using the mid-parental method: average the mother and father, then add about 13 cm (5 in) for a boy or subtract it for a girl. A father 178 cm and mother 162 cm tall points to roughly 176.5 cm (5 ft 9 in) for a son, or about 163.5 cm (5 ft 4 in) for a daughter. Switch between metric and imperial units, choose the child's sex, and read off both the single predicted height and the realistic plus-or-minus range around it, plus an optional plain mid-parental average with no sex adjustment.
What is the Height Calculator?
The mid-parental method 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 usually lands near the genetic midpoint between their mother and father. Because adult men are on average taller than adult women, the formula adds about 13 cm (5 inches) for a boy and subtracts the same for a girl. The result is often called the target height or genetic height, and it is the same quick estimate paediatricians jot down during a growth check.
The single figure the formula returns is the centre of a likely range, not a fixed outcome. Children with the same parents scatter around that midpoint, so this tool shows a band of roughly plus or minus 10 cm (4 inches) around the prediction. Some published sources put the true 3rd to 97th percentile spread slightly tighter, at about plus or minus 8 to 8.5 cm, while others describe the method as accurate to within about 2 inches for roughly 80 percent of children. The honest summary is that mid-parental height is a well-tested rule of thumb, not a lab measurement, so treat any single number as an estimate with meaningful spread on both sides.
Clinics that want a tighter estimate use methods that need more than just parent heights. The Khamis-Roche method factors in the child's own current height, weight, and age alongside the mid-parental figure, and is generally considered more accurate for children over about age four because it tracks the child's actual growth trajectory rather than genetics alone. An even more precise clinical option is bone-age prediction (the Bayley-Pinneau or Greulich-Pyle methods), where a doctor takes a hand and wrist X-ray to see how much growth plate remains; this is the closest thing to a lab-grade forecast but it requires imaging equipment this calculator cannot replicate. A well-known rule of thumb some parents use informally is that a girl's height at around 2 years old, or a boy's height at around 2 to 2.5 years old, is roughly half of their eventual adult height, though this shortcut is far less rigorous than mid-parental or Khamis-Roche and should be treated as a fun approximation, not a forecast.
Many real influences sit outside this formula. Nutrition, general and chronic health, hormone levels, sleep, activity, and especially the timing of puberty all shape final height. Two children with identical parents can still finish several centimetres apart, and a child who hits puberty unusually early or late can land well outside the predicted band even with perfectly typical parents. Improving nutrition and healthcare across generations has also nudged average adult heights upward over the past century in many countries, which is one reason some children now grow taller than both of their parents.
This page also includes a plain mid-parental average mode. That mode skips the sex adjustment and simply averages the two parents, which is handy when you want the neutral genetic midpoint, when comparing siblings of different sexes against the same parental baseline, or when you just want the raw average without any adjustment applied. Switch units at any time and the calculator converts using 1 inch equals 2.54 cm and 12 inches per foot, so you can mix a metric habit with an imperial school record without doing the math by hand.
A predicted adult height is different from a height percentile. Percentile tracks where a child's current height sits among peers of the same age and sex on a growth chart right now, while mid-parental height projects where that child is genetically likely to end up as an adult. A child can sit on a low percentile today and still be tracking exactly toward a modest but perfectly healthy mid-parental target, so the two numbers answer different questions and neither one alone tells the full growth story.
When to use it
- Parents curious about how tall a baby or toddler might grow up to be.
- Comparing a child's predicted adult height against their current growth-chart percentile.
- Helping a teenager understand their likely adult height range during a growth spurt.
- Converting parent heights between centimetres and feet and inches while estimating.
- Checking whether a child growing faster or slower than expected is still tracking toward the family range.
- Getting a quick genetic height baseline before a paediatric growth appointment.
How to use the Height Calculator
- Choose metric (cm) or imperial (feet and inches) units.
- Select the child's sex, then enter the mother and father's heights.
- Pick prediction plus range, or switch to the simple mid-parental average mode.
- Read the predicted adult height and likely range, then copy the result if needed.
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 minus 10 = 166.5 cm, 176.5 + 10 = 186.5 cm
Result: Predicted adult height about 176.5 cm, likely range 166.5 to 186.5 cm.
A girl whose parents are 5 ft 4 in and 5 ft 10 in tall, using imperial units.
- Convert: 5 ft 4 in = 64 in, 5 ft 10 in = 70 in
- Add the parents: 64 + 70 = 134 in
- Subtract 5 in for a girl: 134 minus 5 = 129 in
- Divide by 2: 129 / 2 = 64.5 in, about 5 ft 4 1/2 in (163.8 cm)
Result: Predicted adult height about 5 ft 4 1/2 in, likely range roughly 5 ft 0 in to 5 ft 8 in.
Two siblings, a boy and a girl, from the same 165 cm mother and 182 cm father, using the plain mid-parental average mode for comparison.
- Plain average: (165 + 182) / 2 = 173.5 cm for both siblings as a neutral genetic midpoint
- Boy's sex-adjusted prediction: 173.5 + 6.5 = 180.0 cm
- Girl's sex-adjusted prediction: 173.5 minus 6.5 = 167.0 cm
- Each carries the same roughly plus or minus 10 cm band around their own figure
Result: Neutral midpoint 173.5 cm; boy predicted about 180.0 cm, girl predicted about 167.0 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 |
Quick height conversion reference
| Centimetres | Feet and inches |
|---|---|
| 150 cm | 4 ft 11 in |
| 160 cm | 5 ft 3 in |
| 170 cm | 5 ft 7 in |
| 180 cm | 5 ft 11 in |
| 190 cm | 6 ft 3 in |
Height prediction methods compared
| Method | What it needs | Typical accuracy |
|---|---|---|
| Mid-parental height (this tool) | Both parents heights, child sex | Rough estimate, roughly plus or minus 8 to 10 cm |
| Khamis-Roche method | Parents' heights plus child's current height, weight, age | More precise for children over about age 4 |
| Bone-age X-ray (Bayley-Pinneau) | Hand and wrist X-ray read by a clinician | Most precise, requires clinical imaging |
| Age-2 rule of thumb | Child's height at about age 2 (girls) or 2 to 2.5 (boys) | Informal approximation only |
Common mistakes to avoid
- Treating the number as exact. The prediction is the centre of a wide band, roughly plus or minus 8 to 10 cm (about 3 to 4 inches) depending on the study. A child can comfortably finish several centimetres above or below it, so read it as a ballpark, not a promise.
- Swapping the boy and girl adjustment. You add 13 cm (5 inches) for a boy and subtract the same for a girl. Mixing these up shifts the estimate by about 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, then let the tool convert.
- 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.
- Confusing this with a height percentile calculator. Mid-parental height predicts a future adult height from genetics. It does not tell you where a child sits among peers today; that is a separate growth-chart percentile calculation using the child's own current age and height.
- Assuming step-parents or non-biological guardians count. The formula only works with the biological mother and father's heights, since it relies on genetic inheritance. Entering a step-parent or guardian's height instead of a biological parent's produces a meaningless result.
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 roughly plus or minus 8 to 10 cm depending on the source.
- Khamis-Roche method
- A more detailed height-prediction formula that adds the child's current height, weight, and age to the mid-parental figure, generally used from about age 4 upward.
- Bone age
- An estimate of skeletal maturity from a hand and wrist X-ray, used clinically (Bayley-Pinneau or Greulich-Pyle methods) to predict remaining growth more precisely than parent-based formulas.
- 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.
- Imperial units
- A measurement system using feet and inches, where 1 inch equals 2.54 cm and 12 inches make a foot.
Frequently asked questions
How does this height calculator predict adult height?
It uses the mid-parental method: it averages the mother and father heights, then adds about 13 cm (5 inches) for a boy or subtracts the same for a girl. The result is the centre of a likely adult range of roughly plus or minus 8 to 10 cm.
How accurate is the mid-parental height method?
It is a useful rough guide, not a precise forecast. Most children finish within about plus or minus 8 to 10 cm (roughly 3 to 4 inches) of the estimate, but individual results vary with nutrition, general health, hormones, and the timing of puberty.
Can I use feet and inches instead of centimetres?
Yes. Toggle the units switch to imperial and enter each parent height in feet and inches. The calculator converts using 1 inch equals 2.54 cm and shows the result in both feet and inches and centimetres.
What is the difference between the two modes?
Prediction plus range applies the sex adjustment and shows a likely adult height band. The simple mid-parental average mode just averages the two parents with no sex adjustment, giving the neutral genetic midpoint.
Can a child grow taller than both parents?
Yes. Because the real range spans several centimetres around the estimate, and because nutrition and health have improved across generations, some children end up taller than both parents. The reverse can also happen.
Does this 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, even before birth. For a young child a doctor may instead track growth-chart percentiles using the child's own measurements over time.
What is the Khamis-Roche method and is it more accurate than mid-parental height?
The Khamis-Roche method adds the child's current height, weight, and age to the mid-parental figure and is generally more accurate for children older than about 4, since it accounts for the child's actual growth pattern rather than genetics alone. This calculator uses the simpler mid-parental method, which needs only parent heights and works at any age including before birth.
Is it true a child's height at age 2 predicts their adult height?
It is a widely repeated rule of thumb, not a precise method: a girl's height around age 2, or a boy's height around age 2 to 2.5, is often roughly half their eventual adult height. It is a rough shortcut families use casually, far less rigorous than the mid-parental or Khamis-Roche methods.
Does this height calculator work for adults, or only children?
It is designed to predict a child's future adult height from their parents. If you are already an adult, your height is fixed and this tool has nothing to predict for you; it is only useful for estimating where a still-growing child may end up.
Why does the calculator show a range instead of one exact number?
Because mid-parental height is a statistical estimate, not a measurement. Genetics from two parents combine with many other factors, so real children scatter across a band around the calculated midpoint rather than landing on one exact figure, which is why the range matters as much as the number itself.
Sources
- Predicting a child adult height and growth charts , Nemours KidsHealth
- Assessment of growth: mid-parental height and target range , U.S. National Library of Medicine (PubMed)
- Accurate prediction of children's target height from their mid-parental height , medRxiv preprint