Height Calculator

How tall will I be?

"How tall will I be?" or "how tall will my child be?" are questions that are often asked. A person's height is determined by a combination of genetics and environmental factors, and the precise contribution of the two is complex. Some studies suggest genetics contributes 60%–80%. Normally, a child's height is based on the parental heights subject to regression toward the mean: very tall or short parents are likely to have a taller or shorter child than average, but the child is likely to be closer to the average height than their parents.

Other important factors include nutrition, health, sports activities, and the health and age of the mother during pregnancy. Infants and toddlers grow the fastest; the growth rate declines rapidly from birth to about age 2 and more slowly thereafter. During puberty the growth rate rises again to a second maximum — the pubertal growth spurt — after which it declines to zero, on average at about 15 years old for females and 18 for males. In some cases a person's height begins to shrink in middle age, largely due to the decreased height of the intervertebral discs and degenerative changes.

Predicting a child's adult height

Many methods have been developed to predict a child's adult height, some more accurate than others. Regardless of the method, height prediction is not an exact science, and a child's height can deviate significantly from what is predicted.

Bone age, skeletal maturity method. Bone age can be used to predict height and is considered more accurate than the other methods listed here. The Greulich-Pyle method, for example, compares a left hand and wrist radiograph to the nearest standard radiograph in an atlas of bone age data, and predicts height from the percentage of growth remaining at that bone age. The atlas data were collected between 1931 and 1942 from Caucasian children, which may limit accuracy for current children.

The Khamis-Roche method. This method is considered one of the more accurate height prediction methods that do not require measuring bone age. It is based on the child's stature, weight, and the average stature of the two parents, and the first calculator above is mainly based on it. It is most applicable to Caucasian children between the ages of 4 and 9 who are free from any growth-related condition or disease.

Using growth charts. The CDC growth charts of the United States are good sources for evaluating a child's growth. They consist of percentile curves illustrating the distribution of body measurements of US children, and because children maintain a fairly constant growth curve, the charts can be used to predict adult height to a certain extent.

Simple methods. There are also simple but less accurate methods. One is adding 2.5 inches (6.35 cm) to the average of the parents' heights for a boy and subtracting 2.5 inches for a girl — the second calculator above is based on this method. Another is to double the height achieved by a boy at age 2, or by a girl at 18 months.

How to get taller?

Height is largely (60–80%) determined by genetics, and after the pubertal growth spurt neither boys nor girls typically grow much more — girls typically stop growing by 15 and boys by around 18. Environmental factors still matter while a child is growing. Recommendations for providing the best conditions for the body to grow follow typical healthy-living guidelines:

1. Eat as many unprocessed foods as possible, such as fresh fruits, vegetables, whole grains, proteins, and dairy.
2. Avoid foods high in sugar, trans fats, saturated fats, and sodium.
3. Exercise regularly to strengthen bones and muscles, maintain a healthy weight, and reduce the risk of diseases that could in turn affect growth and height.
4. Pay attention to good posture — a regular slouch can affect actual height in the long term if the back starts curving.
5. Sleep regularly. Human growth hormone is released during sleep, and a regularly poor sleeping schedule during adolescence can affect growth in the long term.

In fringe cases, a disease or condition could be hampering growth, and a doctor may be able to assist. For the most part, peak height is reached once a child has gone through puberty, and any child past puberty will likely maintain their height throughout adulthood.

Frequently Asked Questions

How accurate is a child height prediction?
Height prediction is not an exact science. The regression method used here is most applicable to healthy children between the ages of 4 and 9 (and usable up to about 17.5) who are free of growth-related conditions, and a child's adult height can still deviate significantly from the prediction.

How does the parents-only prediction work?
It averages the mother's and father's heights, then adds 2.5 inches (6.35 cm) for a boy or subtracts 2.5 inches for a girl. It is a simple, less accurate method that also works for unborn children and very young infants.

How do I convert 5 feet 10 inches to centimeters?
Multiply feet by 30.48 and inches by 2.54 and add: 5 feet 10 inches = 5 × 30.48 + 10 × 2.54 = 177.8 centimeters.

References: Khamis HJ, Roche AF, "Predicting adult stature without using skeletal age: the Khamis-Roche method," Pediatrics, 1994. Satoh M, "Bone age: assessment methods and clinical applications," Clinical Pediatric Endocrinology, 2015.