52.6 inches or 133.5 centimeters is the average height for 9 year old boy. He can be higher or smaller than this average height, depending on different factors.
The height of a kid can vary a lot, depending on different factors. As you might know, it is normal for a kid to be a little bit shorter or taller than the average height. Almost all kids go through growth spurts, and they are likely to develop more slowly in height when they are older. These height changes can be clearly seen during their puberty.
Some kids experience earlier puberty than others, while some might have later puberty. In this article, I will talk about the average height for 9 year old boy, an age range that goes through quite a lot of changes in height. Other vital factors influencing their height will also be discussed to help you have a better overview of kids’ average height of this age.
How Does Puberty Affect Growth?
During puberty, boys tend to put up with a growth spurt. Nevertheless, the growth rate can vary greatly as most boys undergo puberty at various ages. But you can expect that almost all boys grow approx. 7.6 centimeters (3 inches) on average each year during this period.
In fact, a boy’s age when he experiences puberty doesn’t impact how tall he will ultimately be. However, it does influence when a child’s growth begins and stops (related: When Do Boys Stop Growing?).
Generally speaking, here are the two most common categories that most boys fall into:
- Early adulthood, the onset of puberty around age 11 or 12 years old
- Late adulthood, the onset of puberty around age 13 or 14 years old
Both types usually reach the same height averaging several inches, but late-maturing individuals tend to grow at a much quicker rate to compensate for lost time. During puberty, boys’ maximum height can reach up to 92% of their adult height.
Boys with growth restrictions before the onset of puberty can still gain the same average amount of inches when it comes to height during their puberty. The fact is that they never compensate for any deficiency from before puberty.
What Factors Can Affect A Kid’s Height And Weight?
One of the biggest factors deciding your child’s height and weight is his/her genes. However, there are still more elements that need to be considered as follows:
- Gestation: If your kids arrived after his/her due date, then they might be bigger than average. On the other hand, they can be smaller if they were born prematurely. This is because multiples are usually early, so they are bound to be smaller too.
- Mother’s pregnancy health: You are more likely to have a smaller baby if you smoked or had a poor eating diet during your pregnancy. In contrast, you tend to get a larger baby if you gained too much weight during your pregnancy or experienced gestational diabetes.
- Formula-fed or breastfed: It is believed that formula-fed babies tend to gain weight more quickly than breastfed babies in their first year, who usually gain weight faster after around 3 months of age. However, breastfed infants might grow faster for the first few months. But by the age of 2, formula-fed and breastfed babies tend to have the same weight.
- Hormones: Hormone imbalance, such as a low level of thyroid or low growth, can cause slow growth in height for your kids.
- Genetic conditions: In addition to your kid’s overall genetic makeup (both you and his/her dad are short, for instance), getting specific genetic conditions, such as Turner syndrome, Noonan syndrome, Down syndrome, etc., can also impact your baby’s growth.
- Gender: In general, baby boys are usually a little bit bigger (weight and length) at birth than baby girls.
- Medicine: Some specific medications, like regular corticosteroid use, can slow down your kids’ growth and development.
- Health problems: If your kids experience a chronic illness (such as cystic fibrosis, kidney disease, cancer, etc.), or any disorder that impacts their ability to absorb nutrients (like gastrointestinal issues), their development can be slowed down.
- Sleep: Infants typically grow and develop after sleeping. So, if your kid is a good sleeper, he/she might also have a good growth rate.
What’s The Average Height For Boys?
According to MDHealth, the average height for a 9 years old boy in the US is 52.5 inches (approx. 133 centimeters). However, you should note that the average height might be affected by a lot of different things, as mentioned above. In addition, the average height for boys can also be considered using a chart or a BMI calculator as follows:
| Age (years) | 50th percentile height for boys (inches and centimeters) |
| 8 | 50.4″ (128 cm) |
| 9 | 52.6″ (133.5 cm) |
| 10 | 54.5″ (138.5 cm) |
| 11 | 56.4″ (143.5 cm) |
| 12 | 58.7″ (149 cm) |
| 13 | 61.4″ (156 cm) |
| 14 | 64.6″ (164 cm) |
| 15 | 66.9″ (170 cm) |
| 16 | 68.3″ (173.5 cm) |
| 17 | 69.1″ (175.5 cm) |
| 18 | 69.3″ (176 cm) |
Weight-for-age percentile for boys
| Age | Weight | Height |
| 2 yrs | 27.5 lbs (12.5 kg) | 34.2″ (86.8 cm) |
| 3 yrs | 31.0 lbs (14.0 kg) | 37.5″ (95.2 cm) |
| 4 yrs | 36.0 lbs (16.3 kg) | 40.3″ (102.3 cm) |
| 5 yrs | 40.5 lbs (18.4 kg) | 43.0″ (109.2 cm) |
| 6 yrs | 45.5 lbs (20.6 kg) | 45.5″ (115.5 cm) |
| 7 yrs | 50.5 lbs (22.9 kg) | 48.0″ (121.9 cm) |
| 8 yrs | 56.5 lbs (25.6 kg) | 50.4″ (128 cm) |
| 9 yrs | 63.0 lbs (28.6 kg) | 52.5″ (133.3 cm) |
| 10 yrs | 70.5 lbs (32 kg) | 54.5″ (138.4 cm) |
| 11 yrs | 78.5 lbs (35.6 kg) | 56.5″ (143.5 cm) |
| 12 yrs | 88.0 lbs (39.9 kg) | 58.7″ (149.1 cm) |
Average weight to height chart for boys (from 1 to 12 years old)
Unlike adults, BMI-related weight and height are measured differently for kids, according to the Centers for Disease Control and Prevention (CDC). And it usually changes with age. Unfortunately, CDC doesn’t provide healthy weight range charts for kids as their weight varies with height growth.
What’s more, a healthy weight for children also tends to change every month. The CDC also recommends that BMI scores don’t directly calculate the body fat percentage. Instead, they are simply a device used to compare the weight and height of kids who are the same age and sex.
Looking at the above growth chart allows you to get a general idea of how your kids are growing. As you can see, percentiles are used to compare your kids’ growth to other kids of the same sex and age.
If you notice, you will see that your kids’ doctor also often measures your baby’s height and weight as a percentile. For instance, the 50th percentile height for a 9 years old boy is 52.6 inches (133.5 centimeters). If your boy is taller than this height, this means he has a greater height than average and vice versa.
Do Boys Develop At A Different Rate Than Girls?
It is generally known that girls and boys develop differently. During childhood, boys tend to develop at a quicker speed than girls. And boys are more likely to be taller than girls on average too. This is also the reason why doctors often use different growth charts for girls and boys to calculate their growth rate over time.
Another thing to remember is that consistency is more important than the percentile that your kids fall into. For example, if your kid drops from the 40th percentile to the 20th percentile, tests will be recommended by their doctors to figure out any underlying cause.
Conclusion
Basically, the average height for 9 year old boy is approx. 52.6 inches (133.5 centimeters) at his 50th percentile. But it should be noted that many elements can influence boys’ growth rate, and eventually, their height. If you are worried about the possibility of development and growth delays, ask your kid’s doctor for advice.
