When Should Puberty Start in Girls and Boys?

There is a wide range of when puberty can start. However, there are typical timeframes for when bodies typically begin to mature for most boys and girls. For some kids, puberty starts earlier or later, which can cause some challenges, particularly emotionally and socially.

Average Age of Puberty

Puberty normally occurs in a series of five stages (Tanner stages) that typically begin between the ages of 8 and 13 for girls and 9 and 14 for boys. For girls, the average age for puberty to start is 10 1/2 years, For boys, it begins at an average age of 11 1/2 to 12 years.

Puberty is considered early (precocious) if it occurs before the expected timing. It is considered late or delayed if it has not begun before the typical age range. Sometimes, medical issues cause an early or late start to puberty. Other times, heredity or unknown factors may be at play.

Recent studies have shown that puberty is occurring at an increasingly earlier age in children. These changes in timing may be due to environmental and other societal factors.

Signs of Puberty in Girls

The first sign of puberty in girls is breast development or thelarche. This begins with breast budding or the formation of small lumps or nodules under one or both nipples. These lumps may be tender and they may be different sizes at first. This is usually also the beginning of a growth spurt.

Next, in about six months, pubic hair develops (also called adrenarche). In some children, pubic hair is the first sign of puberty, and then axillary (armpit) hair begins to grow. Breast size continues to increase and there will be a progressive increase in the development of pubic hair and the external genitalia.

The whole process is completed in three to four years, when an adolescent reaches adult breast and areolar size and an adult pattern of pubic hair. A child will have also reached their final adult height about two years after menarche.

Signs of Puberty in Boys

Typically, the first sign of puberty in boys is an increase in the size of the testicles. This is followed a few months later by the growth of pubic hair. Puberty continues with an increase in the size of the testicles and penis and the continued growth of pubic and axillary hair.

Boys undergo their peak growth spurt about two to three years later than girls. This growth usually begins with an enlargement of the hands and feet and is later followed by growth in the arms, legs, trunk, and chest.

Other changes include a deepening of the voice, an increase in muscle mass, the ability to get erections and ejaculate (especially spontaneous nocturnal emissions or "wet dreams"), and in some boys, breast development (gynecomastia). Puberty is also associated with adolescents beginning to have more axillary perspiration and body odor and acne.

Development continues over three to four years, with boys eventually reaching adult testicle and penis size and an adult pattern of pubic hair. This is followed by the development of chest and facial hair. During this three- to four-year period, most boys will grow 13 to 14 inches and gain about 40 pounds.

Early Puberty

Puberty before the age of 8 in girls and before the age of 9 in boys is considered early or precocious puberty. It can be caused by genetic factors, being overweight, some medical conditions, or psychological factors. However, usually, a cause is not known.

Since the consequences of precocious puberty can include depression, earlier sexual activity, an increased risk of substance abuse, and lowered self-esteem, it's important to talk with your pediatrician if your child shows signs that suggest early development, especially in girls. While the consequences of early puberty in boys are not typically as impactful, it is still helpful to talk with your pediatrician.

Delayed Puberty

Puberty is considered late or delayed if it has not begun by the age of 13 years for girls and 14 years for boys. Delayed puberty can be as isolating and upsetting to kids as early puberty, as they watch their friends mature while they lag behind.

Often the cause is genetic, and late puberty tends to run in families. This is called constitutional delayed puberty. Generally, these children will go through puberty, it just may take a few years longer than what is typical.

Hormonal issues can also delay physical maturation. Some children have a condition called isolated gonadotropin deficiency (IGD), which is a chronic reduction in two important puberty hormones, luteinizing hormone (called LH) and follicle-stimulating hormone (called FSH). Signs of this condition in boys include having a smaller than normal penis and testes and failure to start puberty by age 17.

Developing late may also be a hormonal issue for girls. Girls may be low in LH or FSH. They also may have an issue with their ovaries called primary ovarian insufficiency. This results in deficient levels of the hormone estrogen being produced and released. The causes of primary ovarian insufficiency include injury to the ovaries or chromosomal issues, such as Turner syndrome.

Excessive exercise, eating disorders, anorexia nervosa and patterns of extreme dieting, and low body weight can also delay puberty in both boys and girls. However, this issue is far more commonly seen in girls. Athletes who participate in rigorous training programs for sports like gymnastics and dance sometimes go through puberty late, as well.

Have your pediatrician thoroughly evaluate your teen if they have not shown any signs of puberty by age 13 for girls and 14 for boys. Potential treatments include hormonal therapies.

A Word From Verywell

Puberty is a huge time of transition for kids and parents. Along with the expected growth and development, the teen years can be a wild roller coaster ride physically, socially, and emotionally.

Knowing more about what changes to expect and when can help you and your child feel more comfortable about this transitional period—and keep your bond strong. This is also a good time to learn about common concerns teens face, such as acne, bullying, and mental health concerns including stress, sleep issues, self-harm behaviors, substance use, anxiety, depression, and eating disorders.​

Studies tell us that having a solid parent-teen relationship and strong communication help kids thrive during adolescence. So, while talking about the process of puberty and the big changes that go along with it can feel awkward, keeping an open dialog on this topic can really pay off.