Height Calculator

How tall will I be? How the height calculator works

This height calculator predicts a child's adult height in two ways. With the child's current measurements, it uses the Khamis-Roche method, a regression formula built from the child's age, sex, height, and weight plus the average height of both parents. With the parents' heights only, it uses the midparental height method, which also works for babies and unborn children.

Height predictor using the Khamis-Roche method

The Khamis-Roche height predictor estimates adult height (in inches) as:

Adult height = β₀ + β₁ × child's height (in) + β₂ × child's weight (lb) + β₃ × midparent height (in)

The coefficients β₀ to β₃ follow the Khamis-Roche (1994) regression and differ by sex and by age, in half-year steps from 4 to 17.5. For an age between two steps, such as 5.2 years, the calculator interpolates between the 5.0 and 5.5 predictions. Metric inputs are converted to inches and pounds first, and the result is shown in both feet and inches and centimeters.

The method was developed from white American children in the Fels Longitudinal Study, and its authors limit it to white American children without conditions that affect growth. Below age 4, where the method does not apply, the calculator relies on the midparental height instead. Because the coefficients for 17.5 are reused at 18, predictions for older teens should stay close to their current height. A prediction is never shown below the child's current height.

Mid-parental height calculator: height from parents' heights

The midparental method averages the parents' heights and adjusts for sex:

• Boy: (mother's height + father's height) ÷ 2 + 2.5 in (6.35 cm)
• Girl: (mother's height + father's height) ÷ 2 − 2.5 in (6.35 cm)

For a 5 ft 2 in mother and a 5 ft 10 in father, the average is 5 ft 6 in, so a boy is predicted to reach 5 ft 8.5 in and a girl 5 ft 3.5 in. About 95% of children end up within 4 inches of this target, which the calculator shows as the target range.

What the adult height calculator shows

• Predicted adult height in feet and inches and in centimeters.
• Growth remaining—the predicted height minus the current height.
• Adult height reached—the child's current height as a percentage of the prediction.
• The midparental height and a chart comparing the parents, the child today, and the prediction.

Limitations of height prediction

Genetics explain much of the variation in adult height, but nutrition, sleep, health, and the timing of puberty matter too, and children often end up closer to the average height than their parents. Any height prediction calculator gives an estimate, not a guarantee. Methods based on bone age X-rays, read by a doctor, are more accurate. If you are concerned about a child's growth, talk to a pediatrician.

Frequently asked questions

How tall will I be?

Enter your age, sex, current height, weight, and your parents' heights. If you are between 4 and about 17, the Khamis-Roche method estimates your adult height. Once growth has stopped—usually around 15 for girls and 18 for boys—your current height is your adult height.

How accurate is a height predictor?

The Khamis-Roche method is among the more accurate methods that do not need an X-ray, but individual results can still differ by several inches. The midparental method is simpler and less precise.

Can I predict my baby's future height?

Yes. Use the "Parents' heights only" tab, which needs only the mother's and father's heights. It shows the expected adult height for both a boy and a girl.

Why does the calculator ask for weight?

Weight is one of the three predictors in the Khamis-Roche formula. Its coefficient is small and, at almost every age, negative: for two children of the same age and height, the heavier child gets a slightly lower prediction.