Growth during puberty happens over an extended period, so it can be difficult to know when it has finished. We explain what to expect and how to know when boys are likely to stop growing.

Every individual grows at different rates, and puberty begins and ends at different times for everybody. Puberty can last anywhere from 2 to 5 years, so it is not always easy to predict when it will end.

A boy's body goes through many changes during puberty. These changes can be embarrassing or confusing, but the process happens to everyone and knowing what to expect can help.

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On average boys start puberty around the age of 12 and it can last from 2 to 5 years.

Puberty is the process of growth and change that happens in the body as boys become adults.

Puberty is different for everyone and can start at any age between 8 and 14. The average age for boys to show the first signs of puberty is around 12 years old, about 1 year after girls begin puberty.

The fastest rate of growth is usually 1 to 2 years after puberty has started.

Developing physically into an adult takes 2 to 5 years. Most boys will stop growing taller by age 16 and will usually have developed fully by 18.

Onset of puberty and ethnicity

There is more research on the age that puberty begins in girls than there is for boys. However, a study by the American Academy of Pediatrics found that African-American boys were likely to start puberty earlier than Hispanic or Caucasian boys.

Genes play a role, and parental height is a good indicator of how tall a child will be.

A way to judge roughly how tall a boy will become is to:

  • add together the height of the mother and father in inches
  • divide this number by 2
  • add 2.5 inches

This calculation is approximate and, in general, it is not possible to predict height accurately. Growth does tend to follow a curve, however, so if a person regularly plots a boy's height on a graph throughout their childhood, it may be possible to track where the line is likely to end up.

Chronic illnesses, such as severe arthritis, and genetic conditions, such as Down syndrome, can cause a person to be shorter in adulthood than would otherwise be expected.

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Boys may need reassurance that growing takes time and everyone is different.

Average height varies across the world. In the United States, the average height for an adult man is 5 feet 9 inches or 70.8 inches.

This average is found by adding the height measurements of a group of people together and then dividing by the number of people surveyed.

It does not mean that people above or below this height are unusually tall or small. It is important to remember that everyone is different.

Puberty can be a very confusing time for young people, and the following is a list of questions that people may ask.

At what age do the genitals finish growing?

For boys, one of the first signs of puberty is the growth of the testicles and development of pubic hair. The genitals grow throughout puberty.

Because puberty ends at different ages for different people, there is no set age at which the genitals will have completely developed. Once puberty is complete, the genitals are usually fully developed. Puberty usually takes around 4 years.

The key stages of development of the genitals for boys:

  • after 1 year of puberty, the penis and testicles begin to grow in size
  • the genitals continue to grow for a further 1 to 2 years
  • around 4 years after puberty begins, the growth of the genitals should be complete

When does body hair growth stop?

Pubic hair usually grows first, followed by underarm hair after about a year. Facial hair and other body hair will develop after around 2 years of puberty. Development of body hair will usually stop at the end of puberty.

What might impair growth rates?

Factors such as diet and environment can affect growth. Worldwide, children with diets that cause nutritional deficiencies or malnutrition may not grow to be as tall or strong as those who have had plentiful and balanced meals.

Illnesses, genetic conditions, and use of some medications, such as corticosteroids, can all slow or limit growth.

An imbalance of hormones in the body might slow or speed up growth. A parent or caregiver may wish to seek advice from their doctor if a boy:

  • is growing much faster or slower than expected
  • is much shorter or taller than other children their age
  • is growing very tall despite having shorter parents
  • has not started puberty by age 14

An X-ray of the hand and wrist can help judge how much more a child will grow.

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Eating healthfully and keeping active will help a young person reach their full potential height.

All individuals have a maximum potential height. Some things can be done to ensure a person reaches their full potential height, but a person cannot grow beyond this by using supplements or eating certain foods.

Eating a healthful diet and getting enough sleep and exercise is essential. There are many ways to stay active, from joining a sports team to helping with household chores.

Teenagers need 8 to 9 hours sleep a night. A healthful sleep pattern means going to bed at around the same time each night and not staying up too late.

During puberty, boys may be shorter or taller than other boys their age. This can be hard to deal with. Understanding the changes their body is going through and being able to find information about puberty can help.

Boys should be reassured that growing takes time and that everyone is different. Developing good self-esteem through positive family relationships, friendships, hobbies, and interests can all help boys to cope with puberty.