Height Calculator
Enter both parents’ heights and whether the child is a girl or a boy to get a genetic target height with a likely range, or enter a toddler’s height at age 2 to see the doubling-rule guess. Results appear in centimeters and in feet and inches.
Last updated November 4, 2026
Result
Target height about 165 cm (5 ft 4.9 in), range 156.5 to 173.5 cm
| Result | Value |
|---|---|
| Target (mid-parental) height | 165 cm (5 ft 4.9 in) |
| Low end of range | 156.5 cm (5 ft 1.6 in) |
| High end of range | 173.5 cm (5 ft 8.3 in) |
General estimate only, not medical advice. Talk to a qualified health professional about your own situation. Many children finish outside the ±8.5 cm range, and nutrition, health conditions and other genes matter. Ask a paediatrician about any growth concern.
Show the work
Formula: Target = (father + mother − 13 cm) / 2; range = target ± 8.5 cm
- Parents in cm: father 177.8, mother 165.1 (ft and in converted: total inches × 2.54).
- Sum = 177.8 + 165.1 = 342.9 cm; − 13 = 329.9 cm.
- Target = 329.9 / 2 = 164.95 cm (5 ft 4.9 in).
- Range = 164.95 ± 8.5 = 156.45 to 173.45 cm (5 ft 1.6 in to 5 ft 8.3 in; 8.5 cm = 3.3 in each way).
Result: Target height about 165 cm (5 ft 4.9 in), range 156.5 to 173.5 cm
How predicted adult height is worked out
Target = (father + mother ± 13 cm) / 2, range = target ± 8.5 cm
The mid-parental method averages the two parents’ heights after adjusting for the fact that men are taller than women on average. Add 13 cm (about 5 inches) to the parents’ total for a boy, subtract 13 cm for a girl, then halve. The result is the genetic target height, the adult height a child would reach if height were decided by the parents’ heights alone.
Children rarely land exactly on the target, so the calculator also shows a range of 8.5 cm (about 3.3 inches) either side. This is the commonly cited width of the target range. A child can still finish outside it, particularly when growth is affected by illness, nutrition or genes that the parents’ heights do not reveal.
The second method is the doubling rule. A child’s height at age 2 multiplied by 2 gives a quick guess at adult height. It is a rule of thumb: it ignores the parents, the child’s sex and how early or late the child’s growth spurt will come, and this page states no error figure for it.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Also useful alongside this calculator: Ideal Weight Calculator and Body Fat Calculator.
This is an estimate, not medical advice
This calculator gives a general estimate from the published methods listed under Sources. It does not diagnose anything or replace advice from a doctor, dietitian or other qualified health professional, and individual needs differ. This page has not been reviewed by a medical professional.
What this calculator cannot tell you
Neither method measures your child. A paediatrician plots height on a growth chart over several visits and looks at the direction of growth, which says far more than any single prediction. A child who is tracking steadily along a percentile line is usually following their own pattern, even when it differs from the target.
Both methods are meant for children with typical growth. They are not suitable for diagnosing a growth disorder, deciding on treatment or judging whether a child is short or tall for their age. If you are worried about growth, a missed milestone, or a child who has dropped across percentile lines, talk to a paediatrician.
Centimeters, feet and inches
One inch is exactly 2.54 centimeters. If you choose US units the calculator converts each height to centimeters first, applies the formula, then shows the answer both ways, rounded to a tenth of an inch. Switching the unit selector converts the numbers you typed instead of clearing them, and switching back restores them exactly.
Sources
Official and primary sources for the statements on this page. Their authors have not reviewed or endorsed this page.
- Tanner JM, Goldstein H, Whitehouse RH. Standards for children’s height at ages 2-9 years allowing for height of parents. Archives of Disease in Childhood 1970;45(244):755-762. The parent-adjusted approach behind the mid-parental (target) height idea: a child’s expected height is related to the average of the parents’ heights
The formula (father + mother ± 13 cm) / 2 and the commonly cited ± 8.5 cm target range are the widely taught clinical rule of thumb. The Tanner 1970 paper (PubMed 5491878) is the source of the mid-parental method; we could not open a page confirming the exact 13 cm and 8.5 cm constants, so they are described as commonly cited.
The doubling rule (height at age 2 × 2) is a popular rule of thumb. No source was checked for its accuracy, so this page states no error figure for it.
How to use the Height Calculator
- Choose US (feet and inches) or metric (cm) units.
- Pick a method: parents’ heights, or toddler height at age 2.
- For the parents’ method, enter both parents’ heights and choose girl or boy; for the toddler method, enter the height at age 2.
- Read the target height and range (or the doubled height) in both units, open Show the work to check each step, then Copy, Print or Share.
Worked example
A girl whose father is 178 cm and whose mother is 165 cm. The parents add up to 343 cm, minus 13 is 330, and half of that is 165 cm, which is 5 ft 5.0 in. Subtracting and adding 8.5 cm gives a range of 156.5 to 173.5 cm. For comparison, a toddler measuring 86 cm at age 2 doubles to 172 cm, or 5 ft 7.7 in.
| Result | Value |
|---|---|
| Target height (girl, 178 cm and 165 cm) | 165.0 cm (5 ft 5.0 in) |
| Low end of range | 156.5 cm (5 ft 1.6 in) |
| High end of range | 173.5 cm (5 ft 8.3 in) |
| Doubling rule, 86 cm at age 2 | 172.0 cm (5 ft 7.7 in) |
Frequently asked questions
How accurate is the mid-parental height?
It is a population-level guide, so most children finish near the target but many fall outside the range. Nutrition, health conditions and other genes all play a part.
Why does the calculator add or subtract 13 centimeters?
Adult men are about 13 cm taller than adult women on average. The adjustment puts both parents on the same scale as the child before averaging.
Is the doubling rule at age 2 reliable?
Treat it as a rough guess only. It ignores the parents’ heights and when the child’s growth spurt will happen, so it can be well off in either direction.
When should I see a doctor about my child’s height?
Speak to a paediatrician if growth slows, a child crosses down several percentile lines, or you are simply concerned. A prediction here cannot assess any of that.
Are my numbers stored or sent anywhere?
No. The calculation runs in your browser and nothing you enter is saved or uploaded.