Height Calculator

Want to estimate how tall your child might be as an adult? Enter the parents' heights and your child's current measurements into the calculator above. You'll get an estimated adult height in seconds.

This height calculator uses proven formulas to predict a child's adult height based on parental height, current height, age, and sex. The result is an estimate, not a guarantee. Genetics, nutrition, health conditions, and other environmental factors all influence how tall a child actually grows.

Child Height Calculator and What It Estimates

A child height calculator takes a few simple inputs and returns an anticipated adult height. Most tools use one of two approaches: a mid-parental height formula or the Khamis-Roche method.

You'll typically enter:

• Mother's height
• Father's height
• Child's current height
• Child's current weight (for Khamis-Roche)
• Child's age and sex

The calculator then estimates your child's potential adult height. Think of the result as a reasonable midpoint. Most children land within a range of about 2 inches (5 cm) above or below the predicted value, though some fall further outside that window.

No online height predictor can account for every variable. Growth hormone levels, chronic illness, nutrition, and the timing of puberty all shape a child's final height. The estimate helps you set general expectations. It does not replace a pediatric evaluation.

How the Mid-Parental Height Predictor Works

The mid-parental height formula is the simplest and most widely taught method for predicting a child's adult height. Pediatricians have used versions of it for decades.

Target Height From Mid-Parental Formula

The mid-parental formula averages the parents' heights, then adjusts for the child's sex.

For boys: (Mother's height + 13 cm + Father's height) ÷ 2

For girls: (Father's height − 13 cm + Mother's height) ÷ 2

In imperial units, the 13 cm adjustment is roughly 5 inches. The result is called the "target height" or mid-parental height. Most children's adult height will fall within about 8.5 cm (3.3 inches) above or below this target.

This formula is quick and easy. It only needs the mother's height and father's height. The tradeoff is lower accuracy because it ignores the child's current growth trajectory.

Khamis-Roche Method for Adult Height Prediction

The Khamis-Roche method adds more data points for a more accurate height prediction. Developed by Khamis and Roche in 1994, it uses:

• Child's current height
• Child's current weight
• Child's age and sex
• Mother's height and father's height

The method applies age-specific regression coefficients to these inputs. Because it factors in how much the child has already grown, it tends to predict adult height more closely than the mid-parental formula alone.

One key advantage: the Khamis-Roche method does not require a bone age X-ray. That makes it practical for home use. The median error in the original study was about 2.2 cm (just under 1 inch) for children between ages 4 and 17.5.

Keep in mind that this method was validated primarily on a sample of white American children. Accuracy may vary for other populations. It also assumes the child is healthy and growing normally.

Child Height Predictor for Boys and Girls by Age

Boys and girls follow different growth patterns, so a child height predictor handles them separately.

Girls typically grow fastest in early childhood and then experience a major growth spurt between ages 8 and 13. Peak height velocity (the fastest rate of growth) usually happens around age 11 or 12. Most girls are close to their adult height by age 14 or 15.

Boys tend to hit their growth spurt later, usually between ages 10 and 16. Peak growth speed often occurs around age 13 or 14. Many boys continue adding height through age 16 and sometimes into their late teens.

What causes the height differences between boys and girls? The later onset of puberty in boys gives them roughly two extra years of childhood growth before the growth spurt begins. That's the main reason adult men are, on average, about 13 cm (5 inches) taller than adult women.

The calculator adjusts its prediction based on the child's sex and age. A 10-year-old girl who has already begun puberty is on a different timeline than a 10-year-old boy who has not.

Growth Chart Percentile and Average Height

Growth charts plot a child's height against age and show where they stand relative to other children of the same age and sex. The CDC growth charts are the standard reference in the United States for children ages 2 through 19.

A height percentile tells you what percentage of children are shorter. For example:

• 50th percentile means the child is at the median height, taller than half and shorter than half of peers.
• 25th percentile means 25% of children the same age and sex are shorter.
• 90th percentile means 90% are shorter.

Here are some approximate median heights from CDC data:

A single percentile reading matters less than the trend over time. A child who has tracked along the 30th percentile since toddlerhood is likely growing normally. A child who drops from the 70th to the 20th percentile over a year may need evaluation.

If you have concerns about your child's growth, bring the growth chart data to your pediatrician. They can look at the full picture.

Bone Age, Skeletal Maturity, and Height Prediction

Bone age (also called skeletal age) measures how mature a child's bones are compared to their chronological age. A pediatrician orders an X-ray of the left hand and wrist, then compares it to a reference atlas. The two most common reference standards are Greulich-Pyle and Tanner-Whitehouse.

Why does bone age matter for height prediction? Growth plates at the ends of long bones are what allow bones to lengthen. Once these plates close (full skeletal maturity), height growth stops. A child whose bone age is younger than their calendar age has more growing time left. A child whose bone age is advanced may finish growing sooner.

Clinical height prediction methods like the Bayley-Pinneau method combine bone age with current height to produce a more accurate adult height estimate. These require the X-ray, so they are done in a medical setting, not at home.

Our online calculator does not use bone age because it requires clinical imaging. If you want the most accurate height prediction for your child, ask your pediatrician whether a bone age assessment is appropriate.

Height Growth: When Do Children Stop Growing

One of the most common questions from parents and teens: when do children stop growing?

When do girls stop growing? Most girls reach their adult height between ages 14 and 16. Height growth slows significantly about two years after the start of menstruation.

When do boys stop growing? Most boys stop growing taller between ages 16 and 18. Some continue adding a small amount of height through age 18 or even into their early 20s in rare cases.

By 18 years of age, the vast majority of both boys and girls have reached their final adult height.

Do children experience different growth spurts throughout their development? Yes. There are typically three phases:

1. Infancy and early childhood (birth to age 3): Rapid growth. Height roughly doubles in the first few years.
2. Childhood (age 3 to puberty): Steady growth of about 2 to 2.5 inches (5 to 6 cm) per year.
3. Puberty: A major growth spurt adding 3 to 4+ inches per year at peak velocity.

Does the timing of puberty affect a child's final adult height? It can. Children who enter puberty very early may be tall for their age initially but finish growing sooner, sometimes ending up shorter than peers who started puberty later. Late bloomers often catch up or surpass early maturers. The mid-parental and Khamis-Roche formulas do not fully account for puberty timing, which is one reason clinical assessment with bone age can be more precise.

If your child seems unusually tall or short for their age, or if growth has stalled, consult a pediatrician. In some cases, testing for growth hormone deficiency or other conditions is warranted.

Height Converter for Your Calculator Inputs

Our height calculator accepts both feet/inches and centimeters. If you need to convert before entering values, here are the key relationships:

• 1 inch = 2.54 cm
• 1 foot = 30.48 cm
• 1 cm = 0.3937 inches

Quick reference for common heights:

When entering the mother's height or father's height, measure without shoes. Even a 1-inch error in parental height shifts the predicted result. Use the most recent measurement if available.

Medical Calculator Limitations and Estimate-Only Results

This height calculator is an estimation tool, not a medical calculator that provides a diagnosis or clinical recommendation.

What the calculator cannot account for:

• Growth hormone levels or deficiencies
• Chronic health conditions
• Nutritional status
• Genetic conditions affecting growth
• Bone age or skeletal maturity
• The exact timing of puberty

The mid-parental formula and Khamis-Roche method were developed on specific study populations. Accuracy may differ for children of different ethnic backgrounds, children with medical conditions, or children whose growth patterns diverge from population norms.

Environmental factors like nutrition, sleep, and overall health play a real role in a person's height. Two siblings with the same parents can end up at very different heights.

Use this calculator to get a general sense of your child's potential adult height. If you have specific concerns about your child's growth, slow growth velocity, unusually early or late puberty, or a family history of growth disorders, consult a pediatrician. A medical professional can combine clinical examination, growth chart tracking, bone age imaging, and lab work to give a much more accurate and personalized assessment.

Pediatric Growth Factors Beyond Genetics

Nutrition, sleep, and growth hormone

Even with strong genetic potential, a child needs the right environment to reach their full height potential. Three factors matter most:

1. Nutrition: Adequate calories, protein, calcium, vitamin D, and zinc support bone growth. Chronic malnutrition during childhood can permanently reduce adult stature. Conversely, overnutrition and obesity may accelerate skeletal maturity, potentially leading to earlier growth plate closure.
2. Sleep: Growth hormone is released primarily during deep sleep. Children and adolescents need 9 to 12 hours of sleep per night for optimal growth. Chronic sleep deprivation can blunt growth hormone secretion.
3. Growth hormone: The pituitary gland produces growth hormone, which drives linear growth. Growth hormone deficiency is uncommon but treatable. If a child consistently falls below expected growth curves, a pediatrician may test for this condition.

These factors don't override genetics, but they determine whether a child reaches the upper or lower end of their genetic range.

Puberty, adolescence, and height growth

Puberty has an outsized effect on final adult height. The timing of puberty determines when the growth spurt happens and, more importantly, when growth plates close.

• Early puberty: Children who enter puberty early may be tall for their age temporarily. But their growth plates close sooner, and they may end up shorter as adults than predicted by a calculator that assumes average puberty timing.
• Late puberty (puberty later): Children who mature later often appear short relative to peers during adolescence. They typically have a longer growth window and may catch up or even surpass their earlier-maturing peers.

The Khamis-Roche method does not directly account for puberty timing. This is one reason the prediction has a margin of error. If you know your child is experiencing early or late puberty, keep that context in mind when interpreting the result.

During adolescence, boys typically gain about 3 to 4 inches per year at peak growth velocity. Girls typically gain about 2.5 to 3.5 inches per year. After the growth spurt ends, growth slows rapidly and then stops once skeletal maturity is reached.

How Tall Will Your Child Be: Common Questions

Can you predict adult height without bone age?

Yes. The Khamis-Roche method was specifically designed to predict adult height without a bone age X-ray. It relies on the child's current age, sex, height, weight, and both parents' heights. The trade-off is slightly lower accuracy compared to methods that include skeletal age data. For most families, the convenience and reasonable accuracy make it a practical choice.

Does a growth chart replace an adult height calculator?

No. They do different things. A growth chart shows how a child's current height and weight compare to peers of the same age and sex using standardized percentiles. It tracks growth over time. An adult height calculator estimates the child's future height once growth is complete. A growth chart tells you where your child is now. This calculator estimates where they're headed.

When should you see a pediatrician about child growth?

Consider talking to a pediatrician or pediatric endocrinologist if:

• Your child's height consistently falls below the 3rd percentile on standardized growth charts.
• Growth rate has slowed significantly or stalled for more than 6 to 12 months.
• Your child's height percentile has dropped sharply compared to earlier measurements.
• Puberty signs appear very early (before age 8 in girls, before age 9 in boys) or very late (no signs by age 13 in girls, age 14 in boys).
• The predicted height from this calculator seems very different from what the growth chart trajectory suggests.

A pediatrician can assess whether the pattern is a normal variant or something that warrants further evaluation, such as a bone age X-ray or hormone testing. This calculator estimates. A doctor diagnoses.