Height Calculator

Quick Answer

Last updated: 10 November 2026 ·How we calculate this: the mid-parental (target) height method

How This Height Calculator Works

Height runs in families, so the best simple guess of a child’s adult height comes from the parents. This calculator uses the mid-parental height method that pediatricians use to set a child’s “target height”. Enter both parents’ heights and the child’s sex. The calculator averages the parents’ heights, adjusts for the usual height gap between men and women, and gives a likely range around the result.

How to Use the Height Calculator

1. Choose US or metric units.
2. Choose whether the child is a boy or a girl.
3. Enter the mother’s height.
4. Enter the father’s height.
5. Press Calculate and read the target height and likely range.

Mid-Parental Height Formula

• Boy’s target height: (father’s height + mother’s height + 13 cm) ÷ 2
• Girl’s target height: (father’s height + mother’s height − 13 cm) ÷ 2
• Likely range: target ± 8.5 cm, about two standard deviations
• Inches: 13 cm is about 5.1 inches and 8.5 cm is about 3.3 inches; 1 inch = 2.54 cm exactly

The 13 cm figure is the average difference in adult height between men and women. Adding it to the mother’s height turns her into a “male equivalent” for a son; taking it from the father’s height does the opposite for a daughter. This is the version used in the MSD Manual height potential calculator, based on Tanner and colleagues’ 1970 growth standards.

Key Terms

• Mid-parental height: the average of both parents’ heights, often adjusted for the child’s sex.
• Target height: the adult height a child is expected to reach based on the parents’ heights.
• Standard deviation: a measure of spread; about 95% of values fall within two standard deviations of the average.
• Bone age: how mature a child’s bones look on an X-ray, used to judge how much growth is left.
• Regression to the mean: the tendency of children of very tall or very short parents to be closer to average height.

Worked Example

The mother is 5 ft 4 in (64 inches, 162.56 cm) and the father is 5 ft 10 in (70 inches, 177.80 cm).

• Parents’ total = 162.56 + 177.80 = 340.36 cm
• Son: (340.36 + 13) ÷ 2 = 176.7 cm, about 5 ft 9.6 in
• Daughter: (340.36 − 13) ÷ 2 = 163.7 cm, about 5 ft 4.4 in
• Son’s likely range: 168.2 to 185.2 cm (5 ft 6.2 in to 6 ft 0.9 in)

Real-Life Examples

• Curious parents: a 5 ft 4 in mother and 5 ft 10 in father can expect a son of about 5 ft 9.6 in.
• Metric family: a 165 cm mother and 180 cm father give a daughter a target of 166.0 cm.
• Tall family: a 170 cm mother and 190 cm father give a son a target of 186.5 cm (6 ft 1.4 in).
• Growth checks: compare a child’s growth chart with the family target range at a pediatric visit.

Mid-Parental Height vs Other Height Predictions

• Mid-parental height uses only the parents’ heights. It works from birth but has a wide range.
• “Double the height at age 2” is a folk rule of thumb. It is easy but not a medical method.
• Bone age methods use a hand X-ray read by a doctor. They are more precise for older children and are used when growth is a concern.

Target Heights for Common Parent Heights

Each target has a likely range of about 3.3 inches either side.

What Else Affects a Child’s Adult Height

Genes explain most of the difference in height between healthy people, which is why the parents’ heights are a useful guide. But a child’s actual height also depends on nutrition, sleep, long-term illness, some medicines and the timing of puberty. Children who start puberty early often look tall for their age and then stop growing sooner. Late bloomers often catch up.

The method is weakest at the extremes. When both parents are very tall, children tend to be a little shorter than the formula says, and when both parents are very short, children tend to be a little taller. This pull toward the average is called regression to the mean.

Doctors use target height to check if a child’s growth curve fits the family. A child growing well below the range for the parents’ heights may need a check-up. Methods that also use the child’s current height, weight or bone age (an X-ray of the hand) can be more precise for older children.

Common Mistakes to Avoid

• Treating the target as exact. Many healthy children end up 2 to 3 inches above or below it.
• Using guessed parent heights. Measure both parents without shoes if you can.
• Forgetting the sex adjustment. The plain parents’ average is too low for boys and too high for girls.
• Mixing units. Enter feet and inches in US mode and centimeters in metric mode.
• Ignoring growth worries. If a child is far off their growth curve, see a doctor rather than relying on a calculator.

Frequently Asked Questions

References & Sources