Child Height Predictor
Predict how tall your child will be as an adult using the mid-parental height method. Enter the mother's and father's height along with your child's gender to get a predicted adult height range. Supports both centimeters and inches.
The Child Height Predictor is a free, browser-based tool that estimates a child's adult height from both parents' heights using the clinical mid-parental formula. Enter two heights and a gender to get a predicted adult height plus the ±8.5 cm range pediatricians work with. Nothing you type is uploaded or stored.
How the Mid-Parental Height Method Works
The mid-parental height method is the most widely used clinical formula for predicting a child's adult height. Developed from studies of thousands of families, it uses both parents' heights to estimate the genetic potential of their offspring. The formula accounts for the average height difference between males and females (approximately 13 cm or 5 inches) and provides a prediction that falls within a range of about 8.5 cm (3.4 inches) above or below the calculated value.
Height Prediction Formulas
Boys: (Father's Height + Mother's Height + 13 cm) / 2
Girls: (Father's Height + Mother's Height - 13 cm) / 2
Prediction Range: ± 8.5 cm (3.4 inches)
This method predicts the genetic midpoint based on parental height inheritance.
The Science of Height Inheritance
Height is a polygenic trait, meaning it is influenced by many genes working together rather than a single gene. Scientists have identified over 700 genetic variants that contribute to height, and together these account for about 60-80% of the variation in adult height within a population. The remaining 20-40% is determined by environmental factors, primarily nutrition, overall health during childhood, and hormonal balance during puberty.
Children inherit roughly equal genetic contributions to height from each parent, which is why the mid-parental method averages both parents' heights. However, height inheritance is not perfectly predictable because of the complex interplay between many genes and the random nature of which gene variants a child receives. This is why siblings can have noticeably different adult heights despite sharing the same parents.
Factors That Influence Final Height
While genetics sets the range, environmental factors determine where within that range a child ends up. Adequate nutrition is the single most important environmental factor. Children who receive sufficient protein, calcium, vitamin D, and zinc during critical growth periods are more likely to reach their full genetic height potential. Chronic malnutrition or illness during childhood can permanently reduce adult height by preventing bones from reaching their full growth potential.
Sleep also plays a crucial role because growth hormone is primarily released during deep sleep. Children who consistently get inadequate sleep may not produce optimal levels of growth hormone. Physical activity promotes bone health and can contribute to reaching full height potential, though excessive training in very young athletes can sometimes delay growth. Medical conditions affecting the thyroid, pituitary gland, or growth plates can also significantly impact final height.
Growth Patterns and Timing
Children do not grow at a constant rate. Rapid growth occurs during infancy (about 25 cm in the first year), slows during childhood (5-7 cm per year), and then accelerates again during the pubertal growth spurt. Girls typically begin their growth spurt around age 10-11, while boys start around 12-13. The timing of puberty significantly affects final height: children who enter puberty later often end up taller because their growth plates remain open longer, allowing more years of growth.
Accuracy and Limitations of Height Prediction
The mid-parental height method provides a reasonable estimate for most children, but it has limitations. The prediction range of plus or minus 8.5 cm means the actual adult height could vary by as much as 17 cm across the full range. Bone age X-rays and growth velocity calculations performed by pediatric endocrinologists provide more accurate predictions. Children with medical conditions affecting growth, those taking certain medications, or those with unusually early or late puberty may fall outside the predicted range.
Worked Example: Reading a Child Height Predictor Result
A worked case makes the output easier to sanity-check. If a father is 180 cm and a mother is 165 cm, the boys' formula gives (180 + 165 + 13) ÷ 2 = 179 cm. Applying the ±8.5 cm band, the predicted adult range is 170.5 cm to 187.5 cm. For a daughter from the same parents the formula subtracts instead of adds: (180 + 165 − 13) ÷ 2 = 166 cm, with a range of 157.5 cm to 174.5 cm. The single number is the midpoint of the genetic range, not a guarantee, so read the range rather than the midpoint.
Child Height Predictor vs Growth Charts and Bone-Age Methods
A mid-parental predictor answers a different question from a growth chart. This tool projects where a child's genetics point at adulthood; a growth chart tells you where the child sits today against peers of the same age and sex. Pediatricians in the United States plot children aged 2 to 19 on the CDC clinical growth charts, published at cdc.gov/growthcharts, and treat a drop across percentile lines as more informative than any single measurement. Bone-age methods such as Khamis-Roche or a Greulich-Pyle hand X-ray add a third input, skeletal maturity, and are the most accurate of the three, but they need a clinic visit. Use this predictor for the genetic range, the growth chart for the trend, and bone age only when a specialist asks for it.
When to See a Growth Specialist
If a child's height consistently falls below the 3rd percentile for their age and sex, or if their growth rate has noticeably slowed, a pediatric endocrinologist can evaluate whether a medical condition is affecting growth. Conditions like growth hormone deficiency, Turner syndrome, and hypothyroidism are treatable when identified early. The earlier these conditions are detected and treated, the better the outcome for the child's final adult height.
Updated 2026-09-15
When to Talk to a Doctor About Your Child's Growth
A mid-parental prediction is a rough target, not a diagnosis, and a child who lands well above or below it is usually just normal variation. What matters clinically is the trend, not a single measurement. Raise it with your paediatrician if your child crosses two major percentile lines downward on their growth chart, if growth slows noticeably over a year while peers keep climbing, if there is a large unexplained gap between the predicted and measured height, or if puberty seems clearly early or late. Bring previous heights with you — one number tells a doctor very little, while three points over two years tells them almost everything. In the US, clinicians plot children aged 2 and over on the CDC charts and infants under 2 on the WHO charts, which are described at CDC Growth Charts.
Frequently Asked Questions
When should I worry about my child's height?
Worry about the trend, not one measurement. Crossing two major percentile lines downward, a clear slowdown in growth over a year, or puberty that looks obviously early or late are the signals worth raising with a paediatrician. Take past heights with you.
Is a mid-parental height prediction accurate?
It is a target range, not a forecast. It uses only the parents' heights, so it cannot account for nutrition, illness, or the timing of puberty. Children commonly finish above or below it, which is why growth charts tracked over time matter more than any single predicted number.
How accurate is the mid-parental height prediction?
The mid-parental method is accurate within a range of about 8.5 cm (3.4 inches) above or below the prediction for most children. It captures the genetic component but cannot account for nutrition, health conditions, or the timing of puberty, which all influence final height.
Does nutrition affect how tall my child will be?
Yes, significantly. Adequate nutrition, especially protein, calcium, and vitamin D, is essential for reaching genetic height potential. Chronic malnutrition during childhood can permanently reduce adult height. A balanced diet supports optimal growth.
At what age do children stop growing?
Girls typically stop growing around age 14-16, about 2 years after their first period. Boys usually stop growing around age 16-18. However, some individuals may continue growing slowly into their early 20s. Growth plate closure can be confirmed by X-ray.
Can two short parents have a tall child?
It is possible but less common. Height is influenced by many genes, and a child could inherit a combination of taller variants from both parents. Additionally, improved nutrition and healthcare can help a child exceed parental heights. The prediction range reflects this possibility.
Does the child's birth length predict adult height?
Birth length has a weak correlation with adult height. By age 2, a child's height percentile becomes a better predictor of adult height. Children often shift between percentiles during the first two years as they settle into their genetically programmed growth pattern.
How does a child height predictor differ from a growth chart?
A height predictor projects adult height from the parents' genetics, while a growth chart shows where a child stands today compared with peers of the same age and sex. Pediatricians plot ages 2 to 19 on the CDC clinical growth charts and watch the trend across visits. Use both together: the predictor for the target range, the chart for whether growth is on track.
Which height prediction method is the most accurate?
Bone-age methods such as Khamis-Roche or a Greulich-Pyle hand X-ray are the most accurate because they add skeletal maturity to the calculation, but they require a clinic visit. The mid-parental formula used here needs only two numbers and lands within roughly 8.5 cm for most children, which is close enough for everyday planning.