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- Predicts how tall a child is likely to be as an adult from the mother's and father's heights.
- Uses the mid-parental height method that pediatricians use as a quick guide to genetic height potential.
- Shows a likely range of ± 8.5 cm (about 3.3 in), which covers about 95% of children.
- Can add a second estimate from the old doubling rule if you know the child's height at age 2 or 18 months.
How to use the height calculator
Choose boy or girl
The formula adjusts for the average height difference between men and women.
Pick your units
Use feet and inches or centimeters.
Enter both parents' heights
Use measured adult heights if you can. Guessed heights make the estimate less reliable.
Add an early height (optional)
In the advanced section, enter a boy’s height at age 2 or a girl’s height at 18 months for a doubling estimate.
How the adult height prediction works
Mid-parental height
Boys: (father’s height + mother’s height + 13 cm) ÷ 2
Girls: (father’s height + mother’s height − 13 cm) ÷ 2
13 cm (about 5 in) is the average difference between adult male and female height. In inches, use + 5 or − 5.
Likely range
Range = predicted height ± 8.5 cm (about 3.3 in)
About 95% of children reach an adult height within this range of their mid-parental target.
Doubling rule (optional)
Boys: height at age 2 × 2
Girls: height at 18 months × 2
A traditional rule of thumb. It is rough, but a useful second opinion.
Height prediction examples
Example 1: a boy
Father 5 ft 10 in (177.8 cm), mother 5 ft 4 in (162.6 cm).
Boys often end up close to or a little above the average of their parents plus about 2.5 in.
Example 2: a girl with the same parents
Father 5 ft 10 in, mother 5 ft 4 in.
The same parents give a target about 5 in lower for a daughter than for a son.
Example 3: metric and the doubling rule
Father 178 cm, mother 163 cm.
When both methods land close together, you can be a little more confident in the estimate.
What can change a child's final height
Genes set the target, but they are not the whole story. Nutrition, sleep, overall health, some medicines and the timing of puberty all play a part. Children who start puberty early often grow fast at first and stop sooner, while late bloomers can keep growing into their late teens. Most girls reach adult height around 14 to 15 years old and most boys around 16 to 18.
Where a height calculator helps
Curious parents
Get a quick, research-based idea of how tall your child may grow.
Sports planning
Young athletes often wonder if they will grow into a sport. This gives a rough idea, not a guarantee.
Growth check-ups
Compare the target with your child's growth chart before a visit to the pediatrician.
Clothing and furniture
Plan ahead for bed sizes, bikes and desks as your child grows.
This is an estimate, not a diagnosis. If your child is growing much faster or slower than expected, or their height moves across lines on the growth chart, talk to a pediatrician, who may check growth over time or a bone age X-ray. For adults, see the ideal weight calculator and BMI calculator.
Height calculator FAQ
How do I predict my child's adult height?
Add the mother’s and father’s heights. For a boy add 13 cm (5 in), for a girl subtract 13 cm, then divide by 2. Most children end up within 8.5 cm (3.3 in) of that number.
How accurate is the mid-parental height method?
It gives a useful target, and about 95% of children land within ± 8.5 cm of it. It cannot account for nutrition, health or puberty timing, so treat it as a guide.
Does the doubling rule work?
Doubling a boy’s height at 2 or a girl’s height at 18 months is an old rule of thumb. It can be close, but it is less reliable than methods that use the parents’ heights.
When do children stop growing?
Most girls reach adult height around age 14 to 15 and most boys around 16 to 18, a year or two after puberty peaks. It varies from child to child.
Can a child grow taller than predicted?
Yes. Good nutrition, enough sleep and good health help a child reach their potential, and some children end up above the range. Genetics still set most of the limit.
Can I use this to predict my own height?
This method is meant for children who are still growing. Once growth plates have closed, usually in the late teens, height no longer increases.