Child Height Predictor Calculator
Calculate child height predictor quickly with our age & growth tool. Get results based on evidence-based formulas with clear explanations.
Reviewed by Rahul Singh, Health & Wellness Specialist
Formula
Boys: MPH = (Father + Mother + 13 cm) / 2 | Girls: MPH = (Father + Mother - 13 cm) / 2
Where MPH = Mid-Parental Height in cm. The 13 cm adjustment accounts for the average height difference between males and females. Target range is MPH +/- 8.5 cm. When current height is provided, the prediction is refined using age-specific growth percentage data.
Worked Examples
Example 1: Boy Height Prediction from Parents
Problem:Father is 70 inches (5ft 10in), mother is 64 inches (5ft 4in). Their 8-year-old son is currently 50 inches. Predict adult height.
Solution:Mid-Parental Height (Boys):\nFather = 70 in = 177.8 cm\nMother = 64 in = 162.6 cm\nMPH = (177.8 + 162.6 + 13) / 2 = 176.7 cm = 69.6 in\nTarget Range: 176.7 +/- 8.5 cm = 168.2 to 185.2 cm (66.2 to 72.9 in)\n\nCurrent Height Method:\nAt age 8, boys are ~70.5% of adult height\nPredicted = 50 in / 0.705 = 70.9 in (180.1 cm)\n\nBest Estimate: (69.6 + 70.9) / 2 = 70.3 in (178.5 cm)\nGrowth Remaining: 70.3 - 50 = 20.3 inches
Result:Predicted adult height: 70.3 in (5ft 10in) | Range: 66.2 to 72.9 in
Example 2: Girl Height Prediction
Problem:Father is 72 inches, mother is 66 inches. Their 10-year-old daughter is 56 inches. Predict adult height.
Solution:Mid-Parental Height (Girls):\nFather = 72 in = 182.9 cm\nMother = 66 in = 167.6 cm\nMPH = (182.9 + 167.6 - 13) / 2 = 168.8 cm = 66.4 in\nTarget Range: 168.8 +/- 8.5 cm = 160.3 to 177.3 cm (63.1 to 69.8 in)\n\nCurrent Height Method:\nAt age 10, girls are ~82.5% of adult height\nPredicted = 56 in / 0.825 = 67.9 in (172.4 cm)\n\nBest Estimate: (66.4 + 67.9) / 2 = 67.2 in (170.6 cm)\nGrowth Remaining: 67.2 - 56 = 11.2 inches\nPercentile: ~73rd (above average for girls)
Result:Predicted adult height: 67.2 in (5ft 7in) | Range: 63.1 to 69.8 in | 73rd percentile
Frequently Asked Questions
How does the mid-parental height method predict adult height?
The mid-parental height method, also known as the Tanner method, uses the average of both parents heights with an adjustment for the child gender. For boys, the formula adds 13 cm (5 inches) to the mother height before averaging with the father height, reflecting that males are typically taller. For girls, 13 cm is subtracted from the father height before averaging. The predicted height has a target range of plus or minus 8.5 cm (about 3.3 inches), representing approximately two standard deviations. This means roughly 95 percent of children will reach an adult height within this range. While this method accounts for the strong genetic component of height (genetics explain about 60 to 80 percent of height variation), it does not account for nutritional status, health conditions, or the child current growth trajectory.
How accurate are child height predictions?
Height prediction accuracy varies by method and the child age. The mid-parental height method has a margin of error of about plus or minus 8.5 cm (3.3 inches), which means the actual adult height could fall anywhere within a range of 17 cm (6.7 inches). Predictions become more accurate as the child gets older because more of their growth has already been completed. Methods that incorporate the child current height and bone age (skeletal maturity assessed via X-ray) are more accurate than parental height alone. The Bayley-Pinneau method using bone age has accuracy within about 2.5 cm after age 8. The Khamis-Roche method, which uses current height, weight, and parental heights without bone age, achieves accuracy within about 5 cm for most children. No method can perfectly predict adult height because environmental factors, nutrition, and health conditions during growth years can significantly alter the trajectory.
What percentage of adult height is reached at different ages?
Children follow predictable growth patterns relative to their final adult height. On average, boys reach 50 percent of their adult height by age 2, 75 percent by about age 9, 90 percent by age 14, and approximately 99 percent by age 17 to 18. Girls mature earlier, reaching 50 percent by about 18 months, 75 percent by about age 8, 90 percent by age 12 to 13, and approximately 99 percent by age 15 to 16. These percentages are population averages and individual children may deviate based on their growth tempo. Early maturers will reach these milestones sooner but may not end up taller than late maturers. In fact, children who mature later often have a longer growth period and may reach the same or greater adult height. This is why bone age assessment provides better predictions than chronological age alone.
What factors besides genetics influence a child final height?
While genetics account for 60 to 80 percent of height variation, several environmental and health factors play significant roles. Nutrition is the most important modifiable factor, particularly adequate protein, calcium, vitamin D, and zinc intake during growth years. Chronic malnutrition can reduce adult height by 5 to 10 cm or more. Growth hormone levels naturally vary between individuals, and growth hormone deficiency can severely limit height without treatment. Chronic diseases such as celiac disease, inflammatory bowel disease, kidney disease, and severe asthma (or its treatment with corticosteroids) can impair growth. Sleep quality matters because growth hormone is primarily released during deep sleep. Severe psychological stress can suppress growth through cortisol effects. Puberty timing affects growth duration, with early puberty shortening the growth period. Socioeconomic factors, access to healthcare, and geographic location also influence average population heights.
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy