Height Calculator — Free Online Height Prediction Tool
Predict a child's adult height using the mid-parental height method. Enter both parents' heights and the child's biological sex to get an estimated adult height with a typical range.
Predicted Adult Height
Mid-Parental Height Method
Summary: Based on parental heights, the predicted adult height for a male child is approximately 176.5 cm, with a typical range of 168.0 cm to 185.0 cm. Genetics accounts for about 60-80% of final height; nutrition, health, and environment also play roles.
How to Use the Height Calculator
- Select your unit system: Choose Metric (centimeters) or Imperial (feet and inches). Both systems use the same underlying calculation.
- Select the child's biological sex: The formula adds 13 cm for boys and subtracts 13 cm for girls to account for average adult height differences between sexes.
- Enter the mother's height: Input the biological mother's standing height as accurately as possible. Using measured height rather than self-reported height improves prediction accuracy.
- Enter the father's height: Input the biological father's height. If exact height is unknown, use the best available estimate.
- Review the prediction: The calculator displays the predicted adult height, the expected range (plus or minus 8.5 cm), both parents' heights for reference, and their average height. The prediction represents the most likely outcome based on parental genetics.
This prediction provides a general estimate. Actual adult height depends on numerous factors beyond parental height, including nutrition, health status, sleep quality, and physical activity during the growth years.
Mid-Parental Height Formula
For boys:
Predicted Height = (Mother's Height + Father's Height + 13 cm) / 2 For girls:
Predicted Height = (Mother's Height + Father's Height - 13 cm) / 2 Variables Explained
- Mother's Height: The biological mother's adult height. Maternal height is a strong predictor because all children inherit half their genes from their mother.
- Father's Height: The biological father's adult height. Paternal genetics contribute equally to height potential.
- 13 cm (5.1 inches): The average height difference between adult males and females globally. This correction factor adjusts the parental average to the appropriate sex.
- Range (plus or minus 8.5 cm): The standard deviation of the prediction, accounting for the genetic variation that exists even within families. About 68% of individuals will fall within this range.
Step-by-Step Calculation Example
Predicting height for a boy whose mother is 163 cm and father is 180 cm:
- Add mother's and father's heights: 163 + 180 = 343 cm
- Add 13 cm (for a boy): 343 + 13 = 356 cm
- Divide by 2: 356 / 2 = 178 cm (5'10")
- Expected range: 178 - 8.5 to 178 + 8.5 = 169.5 to 186.5 cm
This boy is predicted to reach approximately 178 cm as an adult, with a likely range of 169.5 to 186.5 cm. The parents' average height is 171.5 cm, and the 13 cm male adjustment accounts for the expected sex-based height difference.
Practical Examples
Example 1: The Tanaka Family
Yuki and Kenji Tanaka want to estimate the adult height of their 5-year-old daughter Hana. Yuki is 157 cm and Kenji is 172 cm:
- Formula: (157 + 172 - 13) / 2 = 316 / 2 = 158 cm
- Predicted height: 158 cm (5'2")
- Range: 149.5 - 166.5 cm (4'11" - 5'6")
Hana is predicted to reach approximately 158 cm as an adult. Her pediatrician notes that Hana is currently tracking along the 40th percentile for height-for-age, which is consistent with this prediction. The family plans to ensure adequate nutrition, particularly calcium and protein, to support Hana's growth potential.
Example 2: The Johnson Family
Lisa (170 cm) and Michael (188 cm) Johnson want to predict the height of their 8-year-old son Tyler:
- Formula: (170 + 188 + 13) / 2 = 371 / 2 = 185.5 cm
- Predicted height: 185.5 cm (6'1")
- Range: 177 - 194 cm (5'10" - 6'4")
Tyler is predicted to be quite tall at approximately 185.5 cm. His basketball coach is interested in this projection, though Tyler's parents remind everyone that predictions are estimates and should not drive career expectations. Tyler currently enjoys swimming and soccer, and his parents focus on providing balanced nutrition and adequate sleep to support his growth.
Example 3: The Garcia Family
Rosa (155 cm) and Carlos (168 cm) Garcia are concerned about their 12-year-old daughter Sofia, who seems shorter than her classmates:
- Formula: (155 + 168 - 13) / 2 = 310 / 2 = 155 cm
- Predicted height: 155 cm (5'1")
- Range: 146.5 - 163.5 cm (4'10" - 5'4")
The prediction suggests Sofia will likely reach about 155 cm as an adult, matching her mother's height. Her pediatrician confirms that Sofia is tracking along the 15th percentile, which is consistent with her parental heights and normal growth. Being shorter than average classmates is expected given her parents' heights and is not a cause for concern.
Height Prediction Reference Table
| Mother | Father | Son (predicted) | Daughter (predicted) |
|---|---|---|---|
| 155 cm | 170 cm | 169 cm | 156 cm |
| 160 cm | 175 cm | 174 cm | 161 cm |
| 165 cm | 178 cm | 178 cm | 165 cm |
| 170 cm | 183 cm | 183 cm | 170 cm |
| 175 cm | 188 cm | 188 cm | 175 cm |
Tips and Complete Guide to Height Prediction
How Genetics Influence Height
Height is a polygenic trait, meaning it is influenced by hundreds of genetic variants rather than a single gene. Genome-wide association studies have identified over 700 genetic variants associated with height, each contributing a small effect. Together, genetics explains approximately 60-80% of height variation in well-nourished populations. The mid-parental height method captures the overall genetic contribution by averaging parental heights, but because children inherit a random combination of height-related variants from each parent, siblings can differ significantly in height despite having the same parents.
Maximizing Growth Potential
While you cannot exceed genetic potential, ensuring optimal conditions during growth years helps children reach their full predicted height. Key factors include balanced nutrition with adequate protein, calcium, vitamin D, and micronutrients; sufficient sleep (children need 9-12 hours, teens need 8-10 hours) because growth hormone is released during deep sleep; regular physical activity that promotes bone development; addressing any chronic health conditions promptly; and minimizing exposure to environmental stressors. Malnutrition, chronic illness, and severe psychosocial stress during childhood can permanently reduce adult height below genetic potential.
Limitations of Height Prediction
The mid-parental height method has several recognized limitations. It assumes that both parents have reached their full genetic height potential, which may not be true if either parent experienced malnutrition or health issues during their own growth years. It does not account for the grandparents' heights, which can influence a child's height through genetic recombination. The 13 cm sex adjustment is an average and varies between populations. The method is less accurate for populations where secular trends (increasing average height due to improving nutrition) are still active. Despite these limitations, it remains one of the most widely used and clinically useful height prediction methods.
Common Mistakes to Avoid
- Using self-reported parental heights: People commonly overestimate their height by 1-3 cm. Using measured heights significantly improves prediction accuracy.
- Treating the prediction as exact: The plus or minus 8.5 cm range is substantial. A prediction of 175 cm means the actual height will likely fall between 166.5 and 183.5 cm. Communicate the range, not just the point estimate.
- Applying excessive pressure based on predictions: Height predictions should inform conversations about health and nutrition, not create expectations about sports performance or appearance.
- Using non-biological parent heights: The formula requires biological parent heights, as the prediction is based on genetic inheritance. Step-parent or adoptive parent heights are not relevant for this calculation.
- Ignoring growth trajectory: A child consistently tracking along a low percentile who is growing at a normal rate is likely healthy. A child whose growth rate suddenly slows may need medical evaluation, regardless of predicted adult height.
Frequently Asked Questions
The mid-parental height method predicts adult height with a margin of error of approximately plus or minus 8.5 cm (3.3 inches) for the majority of individuals. This means the actual adult height will fall within this range about 68% of the time (one standard deviation). While genetics account for approximately 60-80% of height variation, environmental factors including nutrition, health during childhood, sleep quality, and physical activity also play significant roles. The method works best when both parents are of average height for their population. For parents at the extremes of height distribution, the prediction tends toward regression to the mean, meaning very tall parents tend to have children who are tall but not quite as tall as them, and vice versa.
While genetics is the primary determinant, several environmental and health factors significantly influence final adult height. Nutrition during childhood and adolescence is critical, as deficiencies in protein, calcium, vitamin D, zinc, and other nutrients can limit growth potential. Chronic illnesses during growth years, including celiac disease, inflammatory bowel disease, kidney disease, and hormonal disorders, can impair growth. Growth hormone deficiency and thyroid disorders directly affect height. Sleep quality matters because growth hormone is primarily released during deep sleep. Regular physical activity promotes bone development, while excessive intense training during puberty (as seen in some elite gymnasts) may temporarily or permanently affect growth. Socioeconomic factors, prenatal health, and exposure to environmental toxins also play roles.
This calculator predicts final adult height, not height at a specific childhood age. Growth does not occur at a constant rate; children experience periods of rapid growth (infancy, puberty) and slower growth between these periods. Girls typically reach their adult height by age 14-16, while boys may continue growing until age 16-18, with some individuals not reaching full height until their early twenties. For age-specific growth assessment, pediatricians use CDC or WHO growth charts that track height-for-age percentiles over time. If you are concerned about a child's growth rate, their pediatrician can plot their measurements on these charts to determine whether growth is proceeding normally.
The mid-parental height formula accounts for the average height difference between adult males and females, which is approximately 13 cm (5 inches) globally. For predicting a boy's adult height, the formula adds 13 cm to the mother's height before averaging with the father's height: (Mother's Height + Father's Height + 13) / 2. For girls, 13 cm is subtracted: (Mother's Height + Father's Height - 13) / 2. This adjustment accounts for the biological sex difference in adult stature. The 13 cm factor is an average; the actual sex difference in height varies between populations and families. Some genetic variants affect height differently in males and females.
Nutrition and exercise cannot increase height beyond genetic potential, but they can help a child reach their full genetic potential. Adequate nutrition during childhood and adolescence is essential for optimal growth. Key nutrients include protein for tissue building, calcium and vitamin D for bone development, zinc for growth hormone function, and iron for oxygen delivery to growing tissues. Regular physical activity, especially weight-bearing exercise, promotes bone development and stimulates growth hormone release. However, once growth plates close (typically by late adolescence), no amount of nutrition or exercise will increase height further. The goal should be ensuring children have the nutritional and physical activity foundation to reach their genetic potential.
Parents should discuss growth concerns with their pediatrician if a child falls below the 3rd percentile for height-for-age on growth charts, if their growth rate slows significantly compared to their previous trajectory (crossing two or more percentile lines downward), if they are much shorter than would be expected based on parental heights, if puberty is significantly delayed (no signs by age 14 in boys or 13 in girls) or significantly early (before age 8 in girls or 9 in boys), or if they have symptoms suggesting an underlying condition such as chronic fatigue, delayed development, or nutritional deficiencies. Early identification of growth disorders allows for timely treatment, which is most effective during the growth years.
Growth charts track a child's height trajectory over time relative to other children of the same age and sex. A child who consistently tracks along the 50th percentile, for example, is expected to reach the median adult height for their population. The percentile a child tracks on is partly influenced by parental heights, so a child of tall parents tracking on the 75th percentile is growing as expected. Growth charts are most useful for identifying deviations from an individual child's established trajectory rather than comparing them to a single predicted value. If a child who has been tracking along the 60th percentile suddenly drops to the 30th, this warrants investigation even if the 30th percentile is technically normal.
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Disclaimer: This calculator is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional for medical guidance.
Last updated: February 23, 2026
Sources
- Centers for Disease Control and Prevention — Growth Charts: cdc.gov/bmi/adult-calculator
- World Health Organization — Child Growth Standards: who.int/europe/news-room/fact-sheets