About the Child Height Predictor
Genes have a big influence on how tall a child grows, and the parents' heights give a rough guide. This child height predictor uses the mid-parental method found in paediatric growth references: add the two parents' heights, add 13 centimetres (5 inches) for a boy or subtract 13 centimetres for a girl, and divide by two. The result is an estimate of adult height with a typical range of about 10 centimetres either side, shown in centimetres, inches and feet. It is a simple guide for curiosity, not a medical prediction.
Updated October 2026
How to use the Child Height Predictor
- 1Choose centimetres or inches.
- 2Choose whether the child is a boy or a girl.
- 3Enter the father's height and the mother's height.
- 4Read the estimated adult height and the likely range.
- 5Remember that the estimate is a rough guide, not a guarantee.
What really affects adult height
Studies of twins and families suggest that around 80 percent of the variation in adult height within a population is inherited, but many genes are involved and their effects combine in complicated ways. Diet and health in childhood have a large effect too. Children who are well nourished and free of long illness reach more of their genetic potential. That is why average heights have risen in many countries over the last century.
Using the estimate sensibly
- Treat the range as the likely outcome, not the single number.
- Use it for fun, planning clothes sizes or friendly bets, not for medical decisions.
- Do not compare children against the estimate or put pressure on them.
- If a child is much shorter or taller than their friends, check their growth chart with a doctor.
Other measurement tools
Use the Height Converter to switch between centimetres, feet and inches, the BMI Calculator and Ideal Weight Calculator for adults, and the Age Calculator to work out a child's exact age in years, months and days. The Unit Converter handles other measurements. All of these give general information and do not replace advice from a health professional.
Features
- Mid-parental height method
- Separate formulas for boys and girls
- Likely range around the estimate
- Results in cm, inches and feet
- Input in centimetres or inches
- Clear checks for unlikely heights
- Runs in your browser
Frequently asked questions
How do you predict a child's adult height?
The mid-parental method averages the parents' heights and adjusts for sex. For a boy, add the parents' heights plus 13 cm and divide by two. For a girl, add the heights, subtract 13 cm and divide by two. With a father of 178 cm and a mother of 165 cm, a son is estimated at 178 cm and a daughter at 165 cm.
How accurate is the prediction?
It is a rough guide. Most children end up within about 10 cm (4 inches) of the estimate, but some are outside that range. Nutrition, health conditions, sleep, puberty timing and the heights of grandparents and other relatives also influence the final height.
Why add or subtract 13 centimetres?
Adult men are on average about 13 cm (5 inches) taller than adult women. The formula adjusts the average of the parents so the estimate fits the child's sex. It is the standard adjustment used in growth charts and many textbooks.
Can this tell me if my child is growing normally?
No. Growth is assessed by a doctor using growth charts and measurements over time. If you are worried about your child's growth, speak to a paediatrician rather than relying on an online estimate.
Does a child's current height give a better prediction?
Sometimes. Doctors may use current height, age, bone age and growth speed for a more careful estimate. A simple calculator like this one only uses the parents' heights, so it cannot account for how the child is growing now.
Does the tool store the heights I enter?
No. The calculation happens in your browser, nothing is saved or sent to a server, and the heights disappear when you close the page.