As girls and boys approach puberty, they start getting conscious of their height, especially when they see their friends getting taller than them.
However, since the age of puberty varies among young boys and girls and so does their age of growth spurts.
Some kids may have a sudden growth spurt at the age of 12 while some have to wait until they turn 16.
Irrespective of whether the growth spurts are early or late, kids have concerns about their height such as until when they can continue to grow and after what age their height will stop growing.
Boys and girls who have had an early growth spurt are worried whether they would not grow any further since they have already had their spurt.
Those who have their growth spurts late after the age of 15 or 16 years, on the other hand, are also worried thinking whether their late growth spurt will turn out to be short-lasting causing them to be shorter in height.
In both cases, the concerns are related to how long the growth spurts will last and when their height will stop growing.
If you are nearing puberty and have had your growth spurt or are yet to see the growth spurt, read further to know until when your height will grow and the age after which your height will stop increasing.
At what age does the height of girls stop increasing?
Girls usually grow at a quicker pace than boys throughout their infancy and childhood. As they reach puberty, their growth rate increases dramatically.
Most girls stop growing and reach their adult height by the age of 14 or 15 years.
The age may vary depending on the onset of puberty in them or the age at which they have their first menstrual periods.
Usually, girls have growth spurts in the initial 1 or 2 years when their menstruation begins. Also, the height of girls stops increasing within a couple of years after their menstruation begins. In most girls, puberty occurs at the age of 8 to 13 years. So, their growth spurts occur at the age of 10 and 14 years. 
By the age of 14 or 15 years, girls reach their adult height after which they stop growing further. However, in some girls, the growth may halt earlier, especially if they have had early puberty.
At what age does the height of boys stop increasing?
Boys tend to grow faster during puberty. Most boys begin puberty as early as at the age of 9 while some may not hit it until they are 15 or 16. 
In most boys, the biggest growth spurt occurs between the ages of 12 and 15 years.
However even if puberty is delayed due to reasons that are not linked to any genetic, metabolic, or endocrinal abnormality, the boys are not likely to have any significant decrease in their height.
At the same time, having late puberty does not mean the growth spurts will last longer.
Whether puberty occurs at an earlier age or later at the age of 16, it is extremely uncommon for boys to have any increase in height after the age of 20. So, most boys reach the peak height at the age of around 16 to 20 years.   
Also, puberty often lasts about 2 to 4 years. However, spending more time in puberty also does not have any favorable effect on the growth of boys. They can not expect to grow taller than other boys who have had short-lasting puberty.
In very rare cases, boys hit puberty in the late teen and continue to grow for a few years into their twenties.
The reason most boys and even girls do not grow in height once they enter their 20s is linked to the fusion of the growth plates in the bones.
Growth plates are the layers of cartilage present at both the ends of the long bones in children and adolescents. They are the part of the bones that grow longer and cause an increase in height. Since these growth plates fuse within a few months or years after puberty, the height of boys and girls stops increasing after a few years following puberty. 
So, in short, it can be assumed that boys grow until the age of 20 years though some variations may exist in the same depending on the factors discussed below.
Factors that influence the increase in height in boys and girls
The height of a person is largely determined by his or her genetics. External factors such as the amount of sleep and the nutrition they receive also play a vital role in determining how tall they can grow.
Here is a brief discussion about the factors that can influence the age until which boys and girls can continue to grow in height.
Genetics plays a key role in determining the height of boys and girls. It can also determine the age at which they will have their growth spurts and the age until which they may continue growing.
It is estimated that nearly 80% of the height of any person is determined by genetics while the remaining 20 % is influenced by other factors. 
If the parents had had delayed puberty and late growth spurts, the children are likely to show similar traits. They may experience delayed puberty or late growth spurts.
Similarly, if the parents had had their height increasing through the early years of their 20s, kids may expect their height to increase in their 20s.
Besides genetics, nutrition can also have a huge influence on the height of children.
Children who do not get an adequate supply of one or more essential nutrients may experience stunted growth. In these cases, they may stop growing in height at a much earlier age than expected.
Protein deficiency is one of the most common nutritional deficiencies that can limit the growth of children. Deficiencies of minerals such as calcium, vitamin D, and vitamin A may also impact growth.
At the same time, an improvement in nutrition and eating foods rich in proteins could have a favorable impact on the growth spurts that may last longer.
In some cases, boys and girls may experience an increase in height beyond the age of 20 and 16, respectively, following an improvement in nutrition. 
The body secretes growth hormone and TSH (thyroid-stimulating hormone) when we are sleeping. These hormones are critical for the proper growth and development of the bones.
Not getting enough sleep is believed to stunt the growth of kids. It may lead to delayed growth spurts that may end too soon causing the boy or girl to stop growing in height earlier than expected.
Hence, children are advised to ensure they get enough sleep of at least 8 hours every night in order to ensure proper secretion of TSH and growth hormone.
This would enable the growth spurts to last longer and create a favorable effect on the development of the bones resulting in an increase in their heights.
Children who are using stimulant medications for the treatment of conditions such as attention deficit hyperactivity disorder (ADHD) may experience a delay in growth. These medications can affect growth spurts due to which the child may stop growing at an earlier age.
An observational study has revealed that there exists a close link between the use of central stimulants for the treatment of ADHD and the stunted growth in children.
This study involved the assessment of 410 children at the age of around 0.9 to 16.1 years. The researchers found that the use of central stimulants led to the temporary shutdown of the growth in terms of height as well as weight. Also, the children could not catch up to their predicted growth even later after the drug was discontinued.
This suggests that some medications may influence the age at which the growth spurts can begin or end. The continued use of central stimulants may cause the height of children to stop growing at an earlier age causing them to be shorter in stature. 
These factors need to be taken into consideration while predicting at what age the child would stop growing.
There are several genetic and chronic conditions that can lead to delayed or stunted growth. Some of these conditions include:
- Thyroid diseases
- Bone diseases
- Turner syndrome
- Down syndrome
- Russell-Silver syndrome
Girls and boys worried about the age at which their height will stop increasing should pay special attention to their diet and nutrition and avoid factors that can cause early shut down of the growth of the bones like reduced sleep. This is expected to help prolong the age until which their height can increase.
Do boys grow at a different speed than girls?
As discussed earlier, the ages of growth spurts and the ages at which boys and girls stop growing are different.
In boys, puberty occurs slightly later than it occurs in girls.
In general, boys enter puberty between the age of 10 to 13 years and experience a sudden growth spurt between the age of 12 and 15 years of age. This means the biggest growth spurt in boys happens about 2 years later than in girls.
Is it possible to prolong the growth spurts?
It is not uncommon for young boys and girls to be inquisitive about the ways to prolong their growth spurts.
Prolonging the growth spurt is expected to help them grow a few inches taller than their expected height.
There is very little they can do to influence their height once their growth plates have fused. However, it is possible to delay the fusion by adopting healthy lifestyle habits as discussed beneath.
- Regular exercise and consuming a healthy and nutritious diet may help to influence your height favorably and help you grow an inch or two taller.
- A small gain in the height is possible by improving your posture. It would straighten your spine, though it won’t help your bones grow longer.
- Your height tends to fluctuate by around 0.3 inches throughout the day. We tend to be taller in the morning when we wake up than when we go to bed to sleep.
The loss of height as the day progresses could be due to the compression on the spine as a result of the physical activities we perform during the daytime.
Performing stretching exercises during the morning hours is likely to reduce the compression effect on the spine and help minimize the loss of height that occurs by the end of the day. 
It should be noted that even with a healthy diet and improved nutrition, the height of most young girls and boys does not increase after the age of 18 to 20, respectively. The growth line in adolescents falls to zero after these ages.  
Exceptions to the average age at which boys and girls stop growing
- Some medical conditions may cause the height of an adult to increase further even during his or her 20s. This may occur due to the delayed closure of the growth plates. 
- When the growth plates do not fuse or remain open even after the age of 18 to 20 years, the height of the boy or girl may continue to increase.
- Children who suffer from gigantism that occurs due to the excessive secretion of growth hormone may continue to grow after the age of 20. 
- Children who suffer from a type of hemochromatosis caused due to the excessive absorption of iron in the intestine may also experience an increase in height in their 20s. 
The height of girls and boys ceases to increase after the age of 18 and 20, respectively. Some variations in the same may exist due to factors such as nutrition, lifestyle, genetic conditions, and disorders they may be suffering from.