Child Height Predictor
Predict a child's adult height from the parents' heights, with the likely range.
About this tool
Choose boy or girl and enter the father's and mother's heights in centimetres or inches. The predictor shows the estimated adult height and the range most children fall into, in both centimetres and feet and inches. Optionally, enter a boy's height at two years or a girl's at eighteen months to compare with the old doubling rule.
How the mid-parental method works
Paediatricians often use the mid-parental height as a quick guide to a child's genetic height potential. Average the parents' heights, then add 6.5 cm for a boy or subtract 6.5 cm for a girl, which allows for the average 13 cm difference between adult men and women. With a father of 178 cm and a mother of 165 cm, a son's predicted height is 178 cm and a daughter's 165 cm. Most children end up within about 8.5 cm either side, so the son's likely range is 169.5โ186.5 cm. The old rule of doubling a boy's height at two, or a girl's at eighteen months, is shown for interest, but it is less reliable. Honest limits: this is an estimate, not a forecast. Nutrition, health, the timing of puberty and plain chance all play a part. More accurate methods use the child's current height, weight and bone age, measured by a doctor. If you are worried about your child's growth, talk to your doctor or health visitor. Not medical advice. The height converter switches between units, the baby age calculator tracks age in weeks and months and the BMI calculator is for adults.
Frequently asked questions
How accurate is the mid-parental height method?
It gives a target range of about ยฑ8.5 cm. Most children end up within it, but individual results vary with health, nutrition and puberty timing.
What is the formula?
Boys: (father + mother + 13 cm) รท 2. Girls: (father + mother โ 13 cm) รท 2. In inches, use 5 instead of 13 cm.
Does doubling a two-year-old's height work?
It is a rough folk rule for boys at two and girls at 18 months. It is less reliable than methods using parents' heights or medical measurements.
Is my data saved?
No. The calculation runs in your browser and nothing is stored or sent.