How to use the height calculator
- Choose Predict adult height or Convert cm ↔ ft/in.
- Pick the units you want to enter: centimeters or feet and inches.
- To predict, choose whether the child is a boy or a girl, then enter the father's height and the mother's height, ideally measured rather than remembered.
- To convert, enter the height in the units you picked.
- Read the predicted adult height and its likely range in both units, or the converted height.
How adult height is predicted
The calculator uses the mid-parental height method published by James Tanner and colleagues in 1970:
The 13 cm (about 5.1 inches) is the average difference in height between adult men and women. Adding it to the mother's height, or taking it off the father's, puts both parents on the same scale as the child before averaging. The ±8.5 cm range is about two standard deviations, meant to cover roughly 95% of children. Heights entered in feet and inches are converted to centimeters first, so both unit systems give the same answer. The formula and range come from Tanner, Goldstein and Whitehouse (1970) and are the ones used in the MSD Manual's clinical calculator.
Worked example
The calculator opens with a boy whose father is 178 cm and mother is 165 cm:
- Add the parents' heights: 178 + 165 = 343 cm.
- Add 13 cm for a boy: 343 + 13 = 356 cm.
- Halve it: 356 ÷ 2 = 178 cm, about 5 ft 10 in.
- Likely range: 178 − 8.5 = 169.5 cm to 178 + 8.5 = 186.5 cm (about 5 ft 7 in to 6 ft 1 in).
For a girl with the same parents: (343 − 13) ÷ 2 = 165 cm, with a likely range of 156.5 to 173.5 cm. In US units, a 5 ft 10 in father and a 5 ft 5 in mother give a boy a predicted height of 5 ft 10 in. The convert mode starts at 175 cm: 175 ÷ 2.54 = 68.9 inches, which is 5 ft 8.9 in.
How reliable is the prediction?
Treat the result as a family target, not a forecast. Children of very tall or very short parents tend to end up a little closer to the average than the formula suggests, a pattern called regression to the mean. Diet, long-term illness, some medicines and the timing of puberty also matter, and siblings with the same parents can differ by more than the whole range. Methods that also use the child's current height and bone age, measured from a hand X-ray, are more accurate, but they need a doctor.
Talk to your child's pediatrician if their growth seems to have slowed or sped up, or if they're far shorter or taller than other children of the same age. Doctors compare children's measurements against the CDC growth charts over time, which says much more than a single prediction.
Height conversion
| Centimeters | Feet and inches | Centimeters | Feet and inches |
|---|---|---|---|
| 150 | 4 ft 11 in | 175 | 5 ft 9 in |
| 155 | 5 ft 1 in | 180 | 5 ft 11 in |
| 160 | 5 ft 3 in | 185 | 6 ft 1 in |
| 165 | 5 ft 5 in | 190 | 6 ft 3 in |
| 170 | 5 ft 7 in | 195 | 6 ft 5 in |
One inch is exactly 2.54 cm, so divide centimeters by 2.54 for inches, then divide by 12 for feet. The table rounds to the nearest inch.
Frequently asked questions
How accurate is the mid-parental height formula?
It gives a reasonable estimate for most children, and about 95% end up within 8.5 cm (3.3 inches) of the predicted height. It works best when both parents' heights are measured and when the child is growing normally. It's less useful for children with a medical condition that affects growth.
Does a child's height at age 2 predict adult height?
A popular rule of thumb says to double a boy's height at age 2, or a girl's at about 18 months. It's a rough guide that often lands near the mid-parental estimate. Neither method can account for health and puberty timing.
Can a child end up taller than both parents?
Yes. Each child inherits a different mix of the many genes that affect height, and better nutrition over generations has made children taller than their parents in many countries. The range shown covers most children, but some will fall outside it.
How do I convert my height from cm to feet?
Divide your height in centimeters by 2.54 to get inches, then divide by 12. The whole number is the feet and the remainder is inches. For 175 cm: 175 ÷ 2.54 = 68.9 inches, which is 5 feet and 8.9 inches.
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