How accurate is this child height predictor?

The mid-parental method is reliable for most children; roughly 95% end up within 4 inches (10 cm) of the predicted target. It works well because genetics account for about 60 to 80 percent of adult height. That said, no single formula captures every variable. Nutrition, sleep habits, chronic illness, and the timing of puberty all play a role. If you want a more precise assessment, ask your pediatrician about bone age testing or the Khamis-Roche method, which factors in the child's current height and weight.

How do you calculate a child's height from parents' heights?

The most common approach is the mid-parental height formula. For boys, add the mother's height and the father's height together, add 5 inches (13 cm), then divide by two. For girls, add both parents' heights, subtract 5 inches (13 cm), and divide by two. The result is your child's predicted adult height, give or take about 4 inches. Pediatricians have used this calculation for decades because it gives a solid genetic baseline.

What is the mid-parental height method?

It's the simplest evidence-based way to estimate how tall your child will be. You take both parents' heights, average them, and adjust upward for boys or downward for girls by 2.5 inches. The idea is straightforward: your child's height is largely a blend of both parents' genetics. It won't account for environmental factors like nutrition or health issues, but as a quick genetic estimate, it's what most pediatricians reach for first.

What is the Khamis-Roche method for predicting height?

The Khamis-Roche method is considered one of the most accurate approaches that doesn't require an X-ray. Developed by researchers Khamis and Roche in 1994 at Wright State University, it uses a child's current age, height, weight, and both parents' heights to predict adult stature through regression analysis. It's generally accurate for children aged 4 to 17 and is especially useful when you want a prediction that accounts for how the child is already growing, not just their genetic baseline.

When do boys stop growing in height?

Most boys experience their biggest growth spurt between ages 13 and 15, during puberty. After that initial surge, growth gradually slows down. The majority of boys reach their full adult height somewhere between 16 and 18 years old. Some continue adding small amounts of height into their late teens or even early twenties, but that's less common. If your son seems to have stopped growing unusually early or late, it's worth mentioning to his pediatrician.

When do girls stop growing in height?

Girls typically hit their growth spurt earlier than boys, usually between ages 10 and 13. Most girls have completed the bulk of their growth by 14 or 15, roughly two years after their first period. After that, they might gain another inch or so, but the major growth is done. Just like boys, there's variation. Some girls finish earlier, some later. Growth chart tracking with a pediatrician is the best way to know where your daughter stands.

Can I predict my child's height at age 2?

There's a common rule of thumb that says you can double a boy's height at age 2 (or a girl's height at 18 months) to estimate adult height. It's surprisingly decent as a rough guess, but it's not particularly scientific. The mid-parental method in our calculator is more reliable because it's based on actual genetic data from both parents rather than a single early measurement. At age 2, children are still growing rapidly, and a lot can change.

How tall will my child be based on their current height?

If you want a prediction that factors in your child's current height, the Khamis-Roche method or CDC growth chart projections are your best bet. Our calculator focuses on the genetic approach, predicting from parents' heights, which works regardless of the child's current age. For a growth-curve-based prediction, your pediatrician can plot your child's measurements on a standardized growth chart and project where they're likely to end up.

Can I increase my child's predicted height?

You can't rewrite genetics, but you can absolutely help your child reach the top of their genetic range. Sleep is critical: growth hormone is released mainly during deep sleep, so kids aged 6 to 13 need 9 to 11 hours nightly. Balanced nutrition matters too, especially protein, calcium, and vitamin D for bone growth. Regular physical activity, particularly weight-bearing exercise like running and jumping, strengthens bones. On the flip side, chronic malnutrition or untreated health conditions can genuinely prevent a child from reaching their full potential.

How do pediatricians predict a child's adult height?

Pediatricians typically use a combination of methods. They'll start with the mid-parental formula for a quick genetic estimate, then track actual growth on CDC or WHO growth charts over time. If there's a concern about abnormal growth, either too fast or too slow, they may order a bone age X-ray. This involves a simple X-ray of the left hand and wrist to assess skeletal maturity. The bone age result, combined with the child's current height, gives the most accurate prediction available without invasive testing.

What is bone age and when is it used for height prediction?

Bone age is a measure of skeletal maturity determined by X-raying the left hand and wrist. It tells doctors how much growth potential remains in the growth plates. A child whose bone age matches their actual age is developing typically. If bone age is ahead, they may stop growing sooner than expected; if it's behind, they may have more growing time left. Pediatric endocrinologists typically order bone age tests when a child's growth pattern doesn't match expectations, for example, unusually short stature or signs of early puberty.

What is the average height for a child by age?

Average heights vary by gender and age. At age 5, boys average about 43 inches (109 cm) and girls about 42.5 inches (108 cm). By age 10, boys average 54.5 inches (138 cm) and girls 54.3 inches (138 cm). At age 15, boys jump to about 67 inches (170 cm) while girls are around 63.7 inches (162 cm). These averages are based on CDC growth chart data for the United States. Your child doesn't need to match these numbers exactly; what matters most is consistent growth along their own percentile curve.

Does this height predictor work for unborn or future children?

Yes. Since the mid-parental method only requires the biological parents' heights, it works perfectly for predicting the height of a child who hasn't been born yet, or even conceived. You don't need the child's current measurements at all. That's one of the advantages of this method over approaches like Khamis-Roche, which need the child's existing height and weight. For couples planning a family, this gives you a reasonable genetic estimate of how tall your children might be.

What other parenting tools do you offer?

We offer a full suite of free tools for parents at every stage. Predict your baby's blood type with our blood type predictor, explore name meanings with our numerology calculator, or find the perfect name using our AI-powered baby name finder. If you're currently pregnant, our due date calculator and pregnancy weight gain tracker are designed to help you stay informed through every trimester.

Medically Validated Formula

Verified by Nurturepedia Health Editorial Board

Child Height Calculator

Free Child Height Predictor: How Tall Will They Be?

Enter both parents' heights for an instant prediction of your child's adult height. We use the mid-parental formula pediatricians trust, which works for boys & girls, any age, even before birth.

Child Height Calculator

Estimate your child's future height using parental genetics.

Child's Gender

Father's Height

Mother's Height

60–80%

Genetics drives adult height

±4 in

Typical prediction accuracy

95%

Children land within range

How to Predict Your Child's Height

The Mid-Parental Height Formula

For Boys(Mom + Dad + 5″) ÷ 2

For Girls(Mom + Dad − 5″) ÷ 2

Result ±4 inches (10 cm). About 95% of children fall within this window.

This child height calculator uses the mid-parental height formula, also called the Tanner method, which pediatricians have used for decades to estimate a child's adult height from both parents' heights.

Why does it work? Because genetics drives between 60 and 80 percent of adult height. The remaining 20 to 40 percent comes from environmental factors, such as nutrition, sleep, health, and physical activity. Your child's final height is mostly a blend of both parents' genes, with lifestyle influencing where they land within that genetic ceiling.

Our calculator above runs this formula instantly. Just enter both parents' heights, in imperial or metric, and the tool does the rest. It also works for predicting the height of a future or unborn child, since the formula only needs parental heights.

Child Height Prediction Methods Compared

Three approaches, ranked by what you have vs. how precise you need to be.

Mid-Parental Formula

Used by This Tool

The most widely used approach for a quick genetic baseline. Average both parents' heights, then adjust +2.5 in for boys, −2.5 in for girls. Requires no measurements of the child.

Accuracy±4 in / 10 cm

RequiresParents' heights only

Best forAny age, future or unborn children

Used byPediatricians & parents

Khamis-Roche Method

Most Accurate (No X-ray)

Developed at Wright State University in 1994. Factors in how the child is already growing, giving a tighter prediction than the mid-parental method alone. Requires a current measurement.

Accuracy±2–3 in / 5–8 cm

RequiresChild's age, height, weight + parents' heights

Best forChildren aged 4–17

Used byPediatric growth specialists

Bone Age Assessment

Clinical Gold Standard

A wrist X-ray reveals skeletal maturity, showing how much growing time remains. The most precise method available, but requires a clinical visit and is reserved for children with growth concerns.

AccuracyHighest (clinical)

RequiresLeft-hand X-ray (Greulich-Pyle atlas)

Best forChildren with growth concerns

Used byPediatric endocrinologists

Quick tip: There is also a “doubling method” — double a boy's height at age 2, or a girl's at 18 months. It's a fun rule of thumb with a wide margin of error, not a clinical tool.

Average Child Height by Age

Based on CDC growth chart 50th-percentile data (United States). Individual variation is always normal.

Age	Boys (in / cm)	Girls (in / cm)
2 yrs	34.2" / 87 cm	33.5" / 85 cm
4 yrs	40.3" / 102 cm	39.5" / 100 cm
6 yrs	45.5" / 116 cm	45.0" / 114 cm
8 yrs	50.5" / 128 cm	50.0" / 127 cm
10 yrs	54.5" / 138 cm	54.3" / 138 cm
12 yrs	58.7" / 149 cm	59.0" / 150 cm
14 yrs	64.5" / 164 cm	63.0" / 160 cm
16 yrs	68.3" / 174 cm	64.0" / 163 cm
18 yrs	69.2" / 176 cm	64.0" / 163 cm

Source: CDC Growth Charts for the United States (NCHS, 2000 revision).

The table shows 50th-percentile values — meaning half of all children that age are taller and half are shorter. Being above or below these numbers isn't a red flag on its own. What pediatricians actually track is whether a child's growth stays consistent on their own curve over time. Jumping or dropping two or more percentile lines between visits is a bigger signal than where the number lands.

What Actually Influences Your Child's Height?

Genetics sets the blueprint. Environment decides whether they build to the full plan.

Genetics (60–80%)

This is by far the largest driver. Taller parents tend to raise taller children, and shorter parents tend to have shorter children. But it's not a perfect copy; a process called regression toward the mean applies, so very tall parents usually have kids who are tall but slightly shorter than themselves, and vice versa. That's completely normal.

Nutrition

Adequate protein, calcium, zinc, and vitamin D are non-negotiable for healthy bone growth. Chronic malnutrition, even mild, sustained nutritional gaps, genuinely prevents children from reaching their genetic potential. This is one of the few environmental factors that can measurably shorten final adult height.

Sleep & Growth Hormone

Growth hormone is released predominantly during deep sleep stages. Children aged 6 to 13 should get 9 to 11 hours nightly; teenagers need 8 to 10. Chronic sleep deprivation during critical growth years is associated with measurably lower final height. It is one of the most underappreciated growth factors.

Exercise & Physical Activity

Weight-bearing activities like running, jumping, and sports strengthen bones and support healthy development. There's no strong evidence that exercise makes children taller than their genes allow, but staying active helps them reach the upper end of their genetic range. Sedentary lifestyles are linked to poorer overall bone density and growth outcomes.

Underlying Health Conditions

Growth hormone deficiency, hypothyroidism, Turner syndrome, celiac disease, and inflammatory bowel conditions can all impair growth if left untreated. On the flip side, precocious puberty may produce a childhood height that is taller but an adult height that is shorter because the growth plates close earlier. If something feels off, a pediatrician can investigate.

When Do Boys and Girls Stop Growing?

One of the most common questions parents have is when their child will finally stop growing. The honest answer: it depends on when puberty starts, and that varies by gender.

Boys

Puberty begins around age 12–13
Peak growth spurt: ages 13–15 (up to 3–4 in/year)
Growth slows significantly after 16
Full adult height typically reached by 17–18
Some continue adding height into early 20s

Girls

Puberty begins around age 10–11
Peak growth spurt: ages 11–13 (up to 3 in/year)
First period signals growth is slowing down
Most girls finish growing by 14–15
After first period: typically 1–2 more inches total

On variation: “Early bloomers” start and stop growing earlier. “Late bloomers” (constitutional growth delay) catch up after a delayed start — both patterns are entirely normal. A pediatrician can assess growth velocity and, if needed, order a bone age X-ray to clarify the timeline.

When to Talk to a Pediatrician About Growth

Most children grow just fine without any intervention. But certain patterns are worth flagging at your next well-child visit. Don't panic if one applies — many turn out to be normal variation — but they're worth a conversation.

Mention it to your pediatrician if:

Your child consistently sits below the 3rd percentile for height relative to their genetic potential
They've crossed two or more percentile lines downward since a previous visit
Growth velocity drops to less than 2 inches (5 cm) per year after age 3
Signs of unusually early puberty appear (before age 8 in girls, before 9 in boys) or puberty is notably late
Their actual height diverges significantly from what the mid-parental prediction suggests, and the gap is widening

A pediatric endocrinologist can run targeted tests — bone age assessment, growth hormone levels, thyroid function — to determine whether there's an underlying cause or whether your child is simply on their own unique timeline.

Continuous tracking matters more than any single number. If you're pregnant and preparing for your baby's first milestones, our pregnancy weight gain calculator monitors healthy fetal growth before birth.

Understanding Height Percentiles

What your pediatrician really means, and why the trend matters far more than the number.

What a percentile actually means: If your child is in the 40th percentile for height, it means 40 out of 100 children the same age and gender are shorter than your child, and 60 are taller. That's the whole definition, nothing more.

3rd

Shorter than 97% of peers

May warrant monitoring. Don't panic, as this often reflects parental genetics.

50th

Exactly average

Taller than half, shorter than half. Perfectly middle of the curve.

97th

Taller than 97% of peers

Not a problem unless growth is accelerating rapidly beyond the curve.

The trend is what pediatricians actually watch

A child consistently at the 25th percentile is growing normally, meaning they're simply on the shorter end, and that's fine. A child who drops from the 60th to the 20th percentile between two visits is a different story. That shift in the curve, not the number itself, is what triggers further investigation.

The CDC provides standardized growth charts for children aged 2 to 20. The WHO publishes separate charts for infants under 2. Your pediatrician plots your child's measurements on these at every well-child visit; it's one of the most important routine screenings they perform.

Curious about other genetic predictions? Our baby blood type predictor explores another fascinating side of inherited biology. Still in the expecting stage? Our due date calculator is the place to start.

Clinical References & Academic Sources

Midparental Height Estimation: Wright, C. M., & Cheetham, T. D. (2012). The strengths and limitations of parental height predictions. Archives of Disease in Childhood, 97(6), 565–568.(View Study)
Khamis-Roche Stature Prediction: Khamis, H. J., & Roche, A. F. (1994). Predicting adult stature without using skeletal age. Pediatrics, 94(4), 504-507.(View Abstract)
Growth Chart Percentiles: Centers for Disease Control and Prevention (CDC) Growth Charts. National Center for Health Statistics (NCHS).(CDC Source)
World Health Organization Growth Standards: WHO Multicentre Growth Reference Study Group. (2006). WHO Child Growth Standards. Geneva: World Health Organization.(WHO Source)

Medical Disclaimer: This child height predictor provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. The mid-parental height formula provides a genetic estimate: actual growth depends on nutrition, health, hormonal factors, and many other variables. If you have concerns about your child's growth, please consult a licensed pediatrician or pediatric endocrinologist.