Height calculator
The mid-parental method averages the parents' heights and shifts the result by sex. It is a rough guide with a wide margin — roughly ±8 cm covers most children.
Result
- Predicted adult height
- 179.0 cm
- In feet and inches
- 5′ 10.5″
- Likely range (±8 cm)
- 171.0 – 187.0 cm
Worked examples
A boy's predicted height
Mother 165 cm, father 180 cm.
- 165 + 180 = 345
- 345 + 13 = 358
- 358 ÷ 2 = 179
About 179 cm, with a range of roughly 171–187 cm.
The mid-parental method
Adult height is strongly heritable, so averaging the parents' heights gives a reasonable central estimate. The 13 cm adjustment — added for boys, subtracted for girls — reflects the average adult height difference between the sexes.
Some versions of the formula adjust the opposite-sex parent's height first and then average. The results are very close, and neither is meaningfully more accurate given how wide the underlying range is.
Why the range matters more than the number
Roughly ±8 cm covers most children, which is a spread of 16 cm. Quoting a single figure to the nearest centimetre implies a precision the method does not have.
Genetics sets a range; what happens within it depends on nutrition, chronic illness, sleep and the timing of puberty. Children who enter puberty late often end up taller than an early prediction suggested, because they spend longer growing.
When to ask a clinician instead
Growth that crosses centile lines on a growth chart, either upward or downward, matters far more than any single predicted endpoint. That is a reason to see a paediatrician, who can assess bone age and growth velocity properly.
This calculator is a rough guide for curiosity, not a clinical tool.
Formula
Boys: (mother + father + 13) ÷ 2 • Girls: (mother + father − 13) ÷ 2
Worth knowing
- Genetics set a range, not a number. Nutrition, health and timing of puberty all move the outcome within it.
Frequently asked questions
How is a child's adult height predicted?
The mid-parental method averages both parents' heights and adds 13 cm for a boy or subtracts 13 cm for a girl. For a 165 cm mother and 180 cm father, a boy's estimate is 179 cm.
How accurate is this prediction?
It gives a central estimate with a range of roughly ±8 cm. Most children land within that, but the spread is wide and the single figure should not be taken literally.
Can a child grow taller than both parents?
Yes, and it is common. Height is influenced by many genes plus nutrition and health, so children regularly fall outside the range their parents' heights suggest.
When do children stop growing?
Typically around 16 for girls and 18 for boys, though it varies. Growth ends when the growth plates fuse, which follows the completion of puberty.
Does the calculator work for very tall or very short parents?
It is least reliable at the extremes, because predictions tend to regress toward average height. Where there is a medical concern, bone-age assessment by a clinician is far more informative.