How to use the baby height predictor
- Enter the mother's height in centimeters (feet × 30.48 + inches × 2.54 if converting).
- Enter the father's height in centimeters.
- Select the baby's sex — adult men and women differ in average height by about 13 cm.
- Press Calculate to see the estimated adult height, its range, and what it means.
Measure without shoes. A 2 cm error in a parent's height shifts the child's estimate by about 1 cm.
How the mid-parental height method works
- For boys: (mother's height + father's height) ÷ 2, then add 6.5 cm
- For girls: (mother's height + father's height) ÷ 2, then subtract 6.5 cm
The result is a midpoint — roughly 68% of children land within ±8.5 cm of it, which is why the calculator reports a range rather than one number. This same formula underlies most child growth potential calculators used informally by pediatricians as a quick reference point, though it's never a substitute for tracking a child's actual growth chart and percentile over time.
How much of height is genetic?
Twin studies attribute roughly 60–80% of height variation to genetics[1], spread across over 700 identified genetic variants — unlike eye color, no small set of genes dominates. The rest comes from nutrition, sleep, chronic illness and hormonal factors during the growing years, all of which feed into what's often called a child's genetic height potential.
When do children stop growing?
Girls typically finish growing between 14–16, boys between 16–18, when growth plates close under the influence of puberty hormones. Growth isn't steady — infants grow ~25 cm in year one, slow to 5–6 cm/year in mid-childhood, then spurt 8–12 cm/year at puberty's peak.
Terms related to height prediction
- Mid-parental height
- The average of both parents' heights, the base figure this formula adjusts up or down depending on the child's sex.
- Growth percentile
- Where a child's height ranks compared to others their age and sex, tracked on a standardized growth chart over time.
- Growth plates
- Areas of developing cartilage near the ends of long bones; height stops increasing once these plates fuse, usually by late adolescence.
- Growth hormone
- A hormone released mainly during deep sleep that drives height increases throughout childhood and puberty.
Limitations of height prediction
- It's a statistical midpoint — individual outcomes vary widely within the normal range.
- It assumes typical growth conditions — chronic illness or nutritional shortfalls aren't accounted for.
- It can't detect medical causes — growth hormone deficiency requires clinical evaluation, not a formula.
Sources
- National Library of Medicine, MedlinePlus Genetics — Is height determined by genetics?
- Centers for Disease Control and Prevention — CDC Growth Charts
Frequently asked questions
It's a well-established estimate, typically accurate to within several centimeters, but it's a starting reference rather than a precise prediction.
Yes, and it's common. Children inherit a mix of alleles, and better nutrition than a parent's generation had can also raise the outcome.
Growth hormone is released mainly during deep sleep, so chronically insufficient sleep during the growing years can affect growth.
No. Exercise supports general health and bone development but doesn't increase final adult height beyond genetic potential.
Yes — the formula only uses parental heights, so it works at any age. For a child already growing, a pediatrician's growth-chart tracking is more informative.