How tall will my child be? A dad of 5 ft 10 in and a mom of 5 ft 4 in point to a son near 69.5 in
The American Academy of Pediatrics gives a simple formula based on the parents' heights. For a boy, add 5 inches to the mother's height, add the father's height and divide by 2. For a girl, subtract 5 inches from the father's height, add the mother's height and divide by 2. The AAP says to expect a margin of error of about 4 inches up or down. With a father of 70 in (5 ft 10 in, 177.8 cm) and a mother of 64 in (5 ft 4 in, 162.6 cm), a son comes out at 69.5 in (176.5 cm), with a target range of 65.5 to 73.5 in (166.4 to 186.7 cm). A daughter comes out at 64.5 in (163.8 cm), with a range of 60.5 to 68.5 in (153.7 to 174.0 cm).
The calculator above adds your child's current height. Enter an age (in years and months) and a height, and it finds where that height sits among children of the same age and sex on the CDC 2000 growth charts, then follows that percentile out to age 20. A boy aged 8 years 3 months who is 50.0 in (127.0 cm) tall is at the 33.0 percentile, and that curve reaches 68.4 in (173.7 cm) at age 20, inside the parent-based range.
Neither number is a promise. The AAP calls its formula a very rough estimate. Treat the result as a plausible neighborhood, and bring your child's measurements to the pediatrician if growth worries you.
When it helps to run the numbers
- After a well-child visit: if the doctor gives you a height percentile, you can see whether the curve it implies fits the heights of the two parents.
- When your child looks small or tall for their age: comparing with the parents' target range shows whether the child is growing in line with the family.
- When one or both parents are unusually short or tall: the formula tends to overshoot at the extremes (see the section on very tall or very short parents below).
- Before puberty: a note of today's percentile makes it easier to see later how the curve moved.
- Before you pay for a growth product or program: knowing how rough the estimates are, and when a pediatrician should look, helps you judge claims.
How to use the calculator
- Pick the sex and enter both parents' heights. Use the biological parents' adult heights. Feet and inches or centimeters both work, and the card on the left shows the height expected from the parents and its target range.
- Add your child's current growth. Enter the age in years and months and the current height. The card on the right shows the percentile, the z-score and the height at age 20 if the child stays on the same percentile. The sentence below compares the two estimates.
- Look at the height wall. Mother, father, your child now and your child as an adult stand at true height ratios. The dashed figure is the parent-based height, the band is its target range, and the short line is the current curve at age 20.
- Read the growth curve. Percentile lines carry your child's dot, the current curve (same percentile), the parents-based curve and the parent-based range at age 20. Move the age slider, or tap the chart, to read all three values at any age.
- Save it. "Copy result" copies the numbers and notes. "Copy link" copies a link that holds your entries after the # only, so nothing is sent to a server.
The math behind it
| Value | Calculation | Example |
|---|---|---|
| Height from parents | [(mother + 5 in) + father] ÷ 2 for a boy; [(father − 5 in) + mother] ÷ 2 for a girl | 69.5 in (176.5 cm) |
| Target range | Height from parents ± 4 in (± 10.2 cm) | 65.5–73.5 in |
| z-score | ((height ÷ M)L − 1) ÷ (L × S), with L, M and S for that age and sex | −0.44 |
| Percentile | Share of a standard normal distribution below z, × 100 | 33.0 |
| Age-20 height on the current curve | M at age 20 × (1 + L × S × z)1/L | 68.4 in (173.7 cm) |
| Parents-based curve | The z-score of the parent-based height at age 20, applied at every age | percentile 48.2 at age 20 |
Adding 5 inches for a boy and subtracting 5 inches for a girl puts both parents on the same scale as the child, then averages them. The calculator uses 5 in = 12.7 cm, so the offset in the centimeter version is half of that, 6.35 cm. The idea of allowing for parents' heights when judging a child's height goes back at least to Tanner and colleagues, who published height standards for ages 2 to 9 in 1970 that took parents' heights into account.
L, M and S are the skewness, median and variation values that the CDC publishes for each sex and month of age. For children 2 years and older the CDC recommends its 2000 growth charts, and for infants under 2 it recommends the WHO Growth Standards, so this tool starts at 2 years 0 months. Ages are counted in completed months, and the verdict uses the digits you see on screen (height to 0.1 in, percentile to 0.1).
Adult height by parents' heights
| Father \ Mother | 60 in | 62 in | 64 in | 66 in | 68 in |
|---|---|---|---|---|---|
| 5 ft 6 in | 65.5 / 60.5 | 66.5 / 61.5 | 67.5 / 62.5 | 68.5 / 63.5 | 69.5 / 64.5 |
| 5 ft 8 in | 66.5 / 61.5 | 67.5 / 62.5 | 68.5 / 63.5 | 69.5 / 64.5 | 70.5 / 65.5 |
| 5 ft 10 in | 67.5 / 62.5 | 68.5 / 63.5 | 69.5 / 64.5 | 70.5 / 65.5 | 71.5 / 66.5 |
| 6 ft 0 in | 68.5 / 63.5 | 69.5 / 64.5 | 70.5 / 65.5 | 71.5 / 66.5 | 72.5 / 67.5 |
| 6 ft 2 in | 69.5 / 64.5 | 70.5 / 65.5 | 71.5 / 66.5 | 72.5 / 67.5 | 73.5 / 68.5 |
Each cell shows boy / girl. The target range for either sex is ± 4 in around the cell value. Because only the sum of the parents' heights matters, a father of 68 in with a mother of 64 in gives the same answer as a father of 66 in with a mother of 66 in. As a conversion example, a father of 5 ft 10 in and a mother of 64 in give 69.5 in (176.5 cm) for a son and 64.5 in (163.8 cm) for a daughter.
Height by age on the CDC 2000 growth charts
This table lists the 5th, 50th and 95th percentile heights for each age, worked out from the CDC stature-for-age values, along with how much the 50th percentile height rises over the following year. Below roughly the 2.3rd percentile (2 SD under the average), MedlinePlus calls a child short in stature.
| Age | Boys 5th · 50th · 95th (in) | Boys next year (in) | Girls 5th · 50th · 95th (in) | Girls next year (in) |
|---|---|---|---|---|
| 2 years | 31.9 · 34.2 · 36.5 | 3.3 | 31.4 · 33.6 · 35.9 | 3.5 |
| 3 years | 35.1 · 37.5 · 40.1 | 2.9 | 34.6 · 37.1 · 39.7 | 2.7 |
| 4 years | 37.6 · 40.4 · 43.1 | 2.6 | 37.0 · 39.8 · 42.7 | 2.7 |
| 5 years | 39.9 · 43.0 · 46.0 | 2.5 | 39.5 · 42.5 · 45.7 | 2.8 |
| 6 years | 42.2 · 45.5 · 48.8 | 2.5 | 42.1 · 45.3 · 48.8 | 2.6 |
| 7 years | 44.6 · 48.0 · 51.6 | 2.4 | 44.5 · 47.9 · 51.7 | 2.4 |
| 8 years | 46.8 · 50.4 · 54.3 | 2.3 | 46.7 · 50.3 · 54.3 | 2.1 |
| 9 years | 48.7 · 52.7 · 56.7 | 2.0 | 48.5 · 52.4 · 56.6 | 2.0 |
| 10 years | 50.5 · 54.7 · 59.0 | 1.9 | 50.2 · 54.4 · 58.9 | 2.4 |
| 11 years | 52.1 · 56.6 · 61.2 | 2.2 | 52.1 · 56.8 · 61.6 | 2.8 |
| 12 years | 54.1 · 58.8 · 63.7 | 2.8 | 54.8 · 59.6 · 64.4 | 2.3 |
| 13 years | 56.5 · 61.6 · 66.7 | 3.0 | 57.4 · 61.9 · 66.4 | 1.3 |
| 14 years | 59.3 · 64.6 · 69.7 | 2.4 | 58.9 · 63.2 · 67.4 | 0.5 |
| 15 years | 61.7 · 67.0 · 71.8 | 1.4 | 59.6 · 63.7 · 68.0 | 0.3 |
| 16 years | 63.3 · 68.4 · 73.0 | 0.6 | 59.8 · 64.0 · 68.2 | 0.1 |
| 17 years | 64.2 · 69.0 · 73.6 | 0.4 | 60.0 · 64.1 · 68.3 | 0.1 |
| 18 years | 64.7 · 69.4 · 73.9 | 0.1 | 60.0 · 64.2 · 68.4 | 0.1 |
| 19 years | 64.9 · 69.5 · 74.1 | 0.1 | 60.1 · 64.3 · 68.5 | 0.0 |
| 20 years | 65.0 · 69.6 · 74.2 | — | 60.1 · 64.3 · 68.5 | — |
The yearly figure compares median heights, so it does not describe how fast one particular child grows. Children hit the pubertal growth spurt at different ages, which makes the average curve look smoother than a real child's spurt. From age 5 on, the largest yearly gain on the median curve is 3.0 in for boys (ages 13 to 14) and 2.8 in for girls (ages 11 to 12); any single child can differ a lot.
Same parents, different heights now
The father is 70 in (177.8 cm) and the mother 64 in (162.6 cm), and the child is 8 years 3 months. Only the current height changes. The parent-based range is 65.5 to 73.5 in (166.4 to 186.7 cm) for a son and 60.5 to 68.5 in (153.7 to 174.0 cm) for a daughter.
| Current height | Boy percentile | Boy at 20 | Girl percentile | Girl at 20 |
|---|---|---|---|---|
| 46.0 in (116.8 cm) | 1.3 | 63.3 in (160.8 cm), below range | 1.4 | 58.7 in (149.1 cm), below range |
| 48.0 in (121.9 cm) | 9.2 | 65.9 in (167.3 cm), in range | 10.4 | 61.1 in (155.2 cm), in range |
| 50.0 in (127.0 cm) | 33.0 | 68.4 in (173.7 cm), in range | 35.4 | 63.4 in (160.9 cm), in range |
| 52.0 in (132.1 cm) | 66.4 | 70.8 in (179.9 cm), in range | 68.3 | 65.5 in (166.4 cm), in range |
| 54.0 in (137.2 cm) | 89.8 | 73.2 in (185.9 cm), in range | 90.2 | 67.6 in (171.7 cm), in range |
A boy at 46.0 in (116.8 cm) is at the 1.3 percentile, below the 2.3rd percentile line, and his current curve reaches 63.3 in (160.8 cm) at 20, under the parent-based range. A result like this is not a diagnosis, and one reading proves little. Measure again, write the dates down and discuss the records with your pediatrician.
Reading percentiles and z-scores
A percentile says where a child falls among 100 children of the same age and sex. At the 33rd percentile, about 33 of 100 would be shorter and 67 taller; the 50th is the middle. MedlinePlus defines short stature as a height 2 standard deviations or more below the average for children of the same sex and age, or below the 2.3rd percentile, meaning that of 1,000 same-sex children born on the same day, 977 are taller.
A z-score expresses the same position in standard deviations. A z of 0 is the 50th percentile, −1 is about the 16th, −2 is about the 2.3rd and +1.64 is about the 95th. The CDC cautions that growth charts are not intended to be used as a sole diagnostic instrument, and the trend over several visits tells more than one point.
When a parent is very tall or very short
Wright and Cheetham (1999) studied 419 children aged 8 to 9. For 90% of them, height fell within 1.5 SDS of the mid-parental height, about two percentile lines on either side. When parents were unusually tall or short, though, their children were less extreme, and mid-parental height predicted them poorly. Of 13 children below the 2nd percentile, 8 were inside the 90% range from mid-parental height, but only 3 stayed inside once the tendency to move toward average was allowed for.
So if both parents are very short and the child is well below the 2.3rd percentile, do not just assume "they take after us"; ask a pediatrician. MedlinePlus notes that when parents are unusually short or tall, more specialized growth charts may be used. For very tall parents, children often end up a bit shorter than the formula says.
How puberty changes the curve
A child who starts puberty earlier may climb percentiles for a while, and a child who starts later may fall behind classmates until the growth spurt arrives. Projecting today's percentile to age 20 can therefore miss badly around puberty, which is the main reason the "current curve" is a plain assumption rather than a forecast.
The AAP advises that breast development before age 8 in girls, or other signs of unusually early puberty, should be evaluated by a doctor. Because growth stops once the growth plates close, the AAP also suggests discussing any concern about growth with your pediatrician as soon as possible.
Other ways to predict adult height
- Bone age. A pediatrician may order an X-ray of the left wrist or hand to estimate how mature the bones are, one of the tests used when a child is much shorter than expected (MedlinePlus). It uses more information than parents' heights alone.
- The Khamis-Roche method. It predicts adult height from the child's height, weight and the parents' heights without bone age. It was built on 433 white children (223 boys, 210 girls) in the Fels Longitudinal Study, and its authors limit it to healthy white US children.
- Doubling the height at age 2. The AAP lists this as a popular rule of thumb but also says it is not a medically validated prediction tool and that no research exists to show its accuracy. For comparison, the 50th percentile boy at age 2 on the CDC chart is 86.9 cm, and double that is 173.7 cm against 176.8 cm at age 20. For girls the AAP suggests doubling the height at 18 months instead; the WHO median for girls at 18 months is 80.7 cm, and double that is 161.4 cm against 163.3 cm at age 20 (doubling a girl's height at age 2, 85.4 cm, would give 170.8 cm). Averages lining up does not mean the rule predicts one child's height.
Measuring height well
- Measure at about the same time of day, barefoot, with heels, back and head against a flat wall or stadiometer and the eyes looking straight ahead.
- Children under 2 are measured lying down. Length lying down runs a little longer than standing height: for a boy at the 50th percentile at age 2, the WHO standards give 87.8 cm lying and 87.1 cm standing.
- Write down the date next to every height. MedlinePlus suggests keeping your own records too, and the percentile only becomes meaningful when you can see its movement over time.
- Measure twice and use the average if the two readings differ.
When to talk to your pediatrician
- Your child appears to be much shorter than most children of the same age, or seems to have stopped growing (MedlinePlus)
- Height is 2 SD or more below average for age and sex (about the 2.3rd percentile or lower)
- Breast development begins before age 8 in a girl, or there are other signs of unusually early puberty (AAP)
- The current-curve height at age 20 sits below the parent-based range and a second measurement says the same thing
Bring dated height and weight records, the parents' heights and the age at which puberty signs began. Those details help the doctor read the growth curve.
Common mistakes
- Entering age in rounded years. The charts use completed months. Rounding up a 7 year 10 month old to 8 shifts the percentile.
- Guessing a parent's height. The formula needs the biological parents' adult heights; filling in an unknown height with an average defeats the purpose.
- Adding the 5 inches the wrong way. Add 5 inches to the mother's height for a boy; subtract 5 inches from the father's height for a girl.
- Reading one measurement as a trend. A move up or down in percentile shows only across several measurements.
- Treating the range edge as a limit. The 4-inch margin is a rough guide, and some children grow beyond it.
Limits
- The parent formula uses only parents' heights. It cannot account for puberty timing, nutrition, illness or individual variation.
- The current curve assumes the child keeps today's percentile to age 20, which can be far off around puberty.
- The CDC stature-for-age values have not changed since the charts were released on May 30, 2000, so they may not reflect more recent children.
- The calculator covers ages 2 years 0 months to 19 years 11 months and counts completed months.
- It is not a diagnostic tool. It cannot tell you whether tests or treatment are needed. If you are worried about growth, talk with your child's health care provider.
As of CDC Growth Charts pages (reviewed September 2, 2024), AAP HealthyChildren (updated 9/30/2026), MedlinePlus "Short stature" (review date 7/1/2025) and the abstracts of the cited papers, checked on October 19, 2026.
Sources
- 01Centers for Disease Control and Prevention. Growth ChartsPairs ages 0 to 2 years with the WHO Growth Standards and ages 2 years and older with the CDC Growth Charts; states the charts are not meant as a sole diagnostic instrument (page last reviewed September 2, 2024)
- 02Centers for Disease Control and Prevention. Growth Charts: Percentile Data Files with LMS ValuesStature-for-age LMS values for ages 2 to 20 years by sex and month of age, unchanged since the May 30, 2000 release; the reference values this calculator uses
- 03American Academy of Pediatrics, HealthyChildren.org. How Tall Will My Child Be? Predicting a Child's Adult HeightThe mid-parental formulas with 5 inches, a margin of error of about 4 inches, the doubling rule of thumb and its caveat, breast development before age 8 (last updated 9/30/2026)
- 04American Academy of Pediatrics, EQIPP. Mid-Parental HeightTarget height range = mid-parental height ± 4 inches (± 10.2 cm)
- 05MedlinePlus Medical Encyclopedia. Short stature2 SD or more below average, or below the 2.3rd percentile; when to contact a provider; bone age X-rays (review date 7/1/2025)
- 06Tanner JM, Goldstein H, Whitehouse RH. Standards for children's height at ages 2-9 years allowing for heights of parents. Arch Dis Child. 1970;45(244):755-762Height standards for ages 2 to 9 that take parents' heights into account
- 07Wright CM, Cheetham TD. The strengths and limitations of parental heights as a predictor of attained height. Arch Dis Child. 1999;81(3):257-260419 children aged 8 to 9; 90% within 1.5 SDS of mid-parental height; children of very tall or very short parents regress toward average
- 08Khamis HJ, Roche AF. Predicting adult stature without using skeletal age: the Khamis-Roche method. Pediatrics. 1994;94(4 Pt 1):504-507Fels Longitudinal Study, 223 boys and 210 girls; no bone age needed; limited to healthy white US children
- 09World Health Organization. Child Growth Standards: Length/height-for-ageLying length to age 2, standing height from age 2 (50th percentile at age 2 for boys: 87.8 cm lying, 87.1 cm standing)
Frequently asked questions
How do I predict my child's adult height?
The American Academy of Pediatrics suggests the mid-parental method. For a boy, add 5 inches to the mother's height, add the father's height and divide by 2. For a girl, subtract 5 inches from the father's height, add the mother's height and divide by 2. The AAP says to expect a margin of error of about 4 inches up or down. Entering your child's age and current height also follows the CDC percentile out to age 20.
A father of 5 ft 10 in and a mother of 5 ft 4 in: how tall will their child be?
The father is 70 in and the mother 64 in. A son comes out at 69.5 in (176.5 cm), with a target range of 65.5 to 73.5 in (166.4 to 186.7 cm). A daughter comes out at 64.5 in (163.8 cm), with a range of 60.5 to 68.5 in (153.7 to 174.0 cm). Actual height depends on when puberty starts and on the child's growth history.
What if the height from the current curve differs from the parent-based height?
If the age-20 height on the current curve falls inside the parent-based range, your child is growing within what the family's heights suggest. If it falls below, measure again after a few months and see whether the percentile keeps dropping. MedlinePlus advises contacting a provider if a child appears much shorter than most children of the same age or seems to have stopped growing.
What does percentile mean?
A percentile shows where a child stands among 100 children of the same age and sex. The 50th percentile is the middle. MedlinePlus defines short stature as a height 2 standard deviations or more below average, or below the 2.3rd percentile, meaning 977 of 1,000 same-sex children are taller.
Will my child definitely end up inside the predicted range?
No. The AAP describes the formula as a very rough estimate, and some children grow outside the range. Wright and Cheetham found that children of unusually tall or short parents were less extreme than their parents, so the formula fits those families less well.
Is doubling the height at age 2 a good shortcut?
The AAP calls it a popular rule of thumb rather than a medically validated prediction tool and says no research exists to show its accuracy. On the 50th percentile curve, a boy at age 2 is 86.9 cm and double is 173.7 cm against 176.8 cm at age 20, while a girl at age 2 is 85.4 cm and double is 170.8 cm against 163.3 cm at age 20.
What ages does the calculator accept?
From 2 years 0 months to 19 years 11 months. The CDC recommends the WHO Growth Standards for children under 2 and the CDC Growth Charts from age 2, and from age 20 the current height is close to adult height. The height from the parents is calculated at any age.
When should I talk to a pediatrician about my child's height?
Talk to your pediatrician if your child seems much shorter than other children of the same age, seems to have stopped growing, or is more than 2 SD below average (about the 2.3rd percentile). The AAP also says breast development before age 8 in girls, or other signs of unusually early puberty, should be evaluated by a doctor. Bring dated height records and the parents' heights.