Boys grow at different speeds, and their height depends on various factors like genetics, food, sleep, and exercise. Most boys stop growing between the ages of 16 and 18 [1, 2, 3], but when puberty starts can affect how long they keep growing. In this article, we’ll explain when boys usually stop growing, what affects their height, and how you can support their growth. By “boys,” we mean those assigned male at birth who experience changes like a deeper voice, facial hair, and growth spurts during puberty. We also understand that not every child grows at their own pace. Key Takeaways Most boys stop growing between 16 and 18 years old, but some might keep growing into their early 20s if they started puberty later [1, 2, 3]. Height is mostly decided by genetics, but eating healthy, sleeping well, staying active, and adding health supplements (with a doctor’s advice) can help boys reach their full potential. Signs that boys have stopped growing include no height changes for over a year, a deeper voice, and fully developed muscles, body hair, and testicles. If your son seems to be growing slower than expected, talk to a doctor to check for health issues or whether supplements can fill any nutritional gaps. At What Age Do Boys Typically Stop Growing? Most boys and people assigned male at birth stop growing between 16 and 18 years old [1, 2, 3]. This happens because the growth plates in their bones, which help them grow taller, close during these years. Some boys might grow a little more after 18, especially if they started puberty later (after age 14), but this doesn’t happen often. It’s possible to grow 1–2 inches after 16 if the growth plates are still open, but by 21, most boys have reached their adult height. [2, 3] As a parent, it’s also helpful to know that height can change slightly throughout the day. For example, your son might seem a little taller in the morning because the discs in his spine decompress while he’s lying down overnight. This isn’t actual growth but just a natural, temporary change. What's the Average Adult Height for Boys? For men in the United States who are 20 years old or older, the average height is about 5 feet 9 inches (69 inches or 175.3 cm) [4]. This is based on the latest data from the National Center for Health Statistics, from 2015 to 2018. The table below shows the average height for boys at different ages, which can help you track your child’s growth as he gets older: Age (years) Average height for boys in the US (inches and centimeters) 8 52 in. (132.1 cm) 9 53.5 in. (135.9 cm) 10 55.8 in. (141.7 cm) 11 58.8 in. (149.3 cm) 12 60.7 in. (154.2 cm) 13 64 in. (162.5 cm) 14 66.6 in. (169 cm) 15 67.8 in. (172.3 cm) 16 68.3 in. (173.5 cm) 17 69 in. (175.2 cm) 18 69 in. (175 cm) 19 68.9 in. (176.1 cm) How Does Puberty Affect A Boy’s Growth? Puberty is an important stage when boys experience major changes in their bodies, including rapid growth. These changes are caused by higher levels of testosterone, a hormone that drives growth and development. Boys usually start puberty between 9 and 14 years old [5]. How Do I Know if Puberty Has Started? You know that puberty has started because of these early signs [5]: Voice changes: Your son’s voice may crack and eventually become deeper. Body hair growth: Hair will start growing under the arms, in the pubic area, and on the face. Testicle and penis growth: The testicles grow larger first, followed by the penis. Growth spurts: Boys may suddenly grow taller, with noticeable changes in their legs, arms, and overall height. More muscle mass: Boys develop broader shoulders and more muscles as they grow. How Long Does Puberty Last? Puberty lasts between 2 and 5 years for most boys [6]. During this time, boys grow faster than at any other point in their lives, except when they are babies. The biggest growth spurts usually happen between the ages of 12 and 15, when boys might grow several inches in just a year or two [6]. How Do I Know if Puberty Is Completed? Even though it can be a little different for each boy, here are usually the signs showing that puberty is completed: Stable height: If your son hasn’t grown taller in over a year, it’s a sign that his growth plates have closed, and he’s reached his adult height. You can use the CDC growth chart for boys to track his height over time and check if it has stayed the same. Comparing his height to the average height for boys his age in the chart can also help you see how he’s developing. Stable shoe size: When your son’s shoe size hasn’t changed for a while. Facial and body hair: By the end of puberty, boys typically have facial hair (if it runs in the family) and body hair on their chest and abdomen. Deeper, steady voice: Their voice becomes permanently deep, with no more cracking or changes. Increased muscle mass: Testosterone helps boys develop stronger muscles, broader shoulders, and a more defined chest. Fully developed testicles and penis: The testicles and penis reach their adult size by the end of puberty. Bone age matches actual age: A doctor can use a bone X-ray (usually of the wrist or hand) to check if the growth plates have closed, which confirms that growth has stopped. Do Early or Late Bloomers Grow Taller? No, early or late bloomers don’t necessarily grow taller [7]. Early bloomers (boys who start puberty before the age of 9) have their growth spurts earlier. However, their growth plates also close earlier, so they stop growing sooner. Late bloomers (boys who start puberty after 14) grow at a slower pace early on but might grow for a longer time, even into their late teens or early 20s. Even though late bloomers grow for more years, their final adult height depends more on genetics, nutrition, and overall health, rather than on when puberty begins. How To Predict a Boy’s Adult Height? Height Predictor Tool Current Height (cm): Current Age: Gender: Male Female Predict Height Height prediction based on growth studies. View sources 1. Monitoring His Growth on a Chart The CDC provides a growth chart that can also help you predict your son’s adult height. These charts plot height (y-axis) against age (x-axis) and include percentile curves. Simply find the point on the graph where his age and height intersect, then follow the nearest percentile line to project his height by age 20. Boys growing between the 3rd and 97th percentiles are generally considered within the normal range, but it’s important to track whether they are staying parallel to their growth curve over time. Example:If your 3-year-old son is about 37 inches (94 cm) tall, he’d fall on the 50th percentile line. This means he’s taller than 50% of boys his age and shorter than 50%. By following the 50th percentile line to the end of the graph, you can estimate that he’ll likely be about 70 inches (178 cm) tall at age 20. How quickly a child is growing (Growth velocity) is also critical. Growth velocity is essentially the slope of the growth curve. If his curve is steady and parallel to the percentile lines, the growth rate is normal. Significant deviations, such as a flattening or steep drop in the curve, may signal an issue worth discussing with your child’s pediatrician. Here’s a helpful video on how to read a growth chart: 2. Using the Average of the Parents’ Heights Genetics has the biggest influence on how tall your son will be [8]. Boys usually inherit their height potential from their parents. If you’re curious about how tall your son might grow, this simple formula, called the mid-parental height method, can give you a good estimate [9]: Predicted Height for Boys (in inches) = Simple Steps to Use the Formula: Adjust both heights for Age Add 0.6 inches (1.5 cm) if either parent is 45–55 years old. Add 1.2 inches (3 cm) if either parent is over 55 years old. Adjust Mother’s Height for Sex: Multiply the mother’s height by 1.08 to account for biological differences between boys and girls. Find the Mid-Parental Height: Add the adjusted heights of both parents and divide by 2 to find the average. Recent research shows that it’s more accurate than it used to be: it predicts about 36–40% of a boy’s height, with the rest influenced by factors like nutrition, health and family traits [9]. What Are the Common Causes of Growth Delays in Boys? The most common things that cause growth delay in boys include: Medical Conditions: Certain health issues, like an underactive thyroid (hypothyroidism) or problems with growth hormone production, can slow down your son’s growth. These conditions affect the hormones his body needs to grow properly. Chronic Illnesses: Long-term health problems like asthma, diabetes, or digestive issues can take a toll on your son’s body, making it harder for him to grow as expected. Poor Nutrition: If your son isn’t getting enough of the right nutrients, like protein, calcium, or vitamin D, it can slow down his growth. A healthy, balanced diet is essential for supporting his body during these important years. Obesity: Being overweight can delay the start of puberty and affect your son’s growth. It can also make it harder for his bones and muscles to develop properly. Natural Growth Stunters: Lack of sleep, high stress levels, smoking, and excessive caffeine intake are other factors that can stunt growth. These habits can interfere with your son’s hormone production, bone development, and overall growth trajectory. When Should You See a Doctor? You should consult your son’s doctor if: He hasn’t shown any signs of puberty by age 14, like a deeper voice or testicle growth. His growth pattern falls below the 3rd percentile or deviates significantly from his usual curve. A pediatrician might recommend a bone age X-ray (usually of the wrist) to better understand your son’s growth. This test compares his "bone age" (physical development) to his chronological age (birth certificate age). If the bone age is younger than the chronological age but the growth curve remains parallel, the doctor may diagnose constitutional growth delay. This condition usually resolves as the child catches up later. If the bone age matches the chronological age but the growth curve is not parallel, it could indicate underlying issues such as genetic conditions (like familial short stature), chronic illnesses, or nutritional deficiencies How Can You Help Your Son Grow? You can help him grow to his full height by making sure he eats healthy, gets plenty of rest, and has regular exercise, even though his height is mostly determined by his genes. 📌 For more tips, check out our blog on how to get taller. 1. Supporting the Right Nutrition Choices Eating a balanced diet gives his body what it needs to build strong bones, and muscles, and stay healthy overall. Key Nutrients for Growth Some nutrients are extra important for helping kids grow: Calcium: Makes bones strong and supports healthy growth. Found in milk, cheese, yogurt, and green vegetables like spinach. Vitamin D: This is one of the best vitamins for growth. It helps the body use calcium. You can find it in foods like salmon, eggs, and milk or cereal that says "fortified with vitamin D" on the label. Protein: Builds muscles and tissues. Good sources include chicken, eggs, fish, beans, and nuts. Depending on their age, NuBest offers specialized growth vitamins tailored for ages 2–4, ages 5–9, and ages 10+. These doctor-recommended supplements are designed to support healthy growth with a blend of essential nutrients. Best Foods for Growth To help your son grow, serve meals with a mix of: Vegetables: For vitamins and minerals. Try options like broccoli, carrots, or leafy greens. Lean Proteins: Like chicken, turkey, fish, eggs, or plant-based proteins like lentils or tofu. Healthy Fats: Found in foods like nuts, seeds, avocados, and olive oil. Jabe Brown, founder of Melbourne Functional Medicine and a highly regarded expert in nutrition and functional medicine, told us: "Pairing calcium supplements with meals containing magnesium or vitamin K2, like leafy greens or dairy, can boost nutrient absorption and ensure the body uses these nutrients efficiently." 📌 Find more guidance on foods to make your boy taller in our guide. What Can You Do When Nutritional Gaps Happen? Whether your son is a picky eater or eats well, he might still miss out on some key nutrients. Research shows that taking a nutritional supplement can help boys who are shorter or leaner than average. For example, a 2023 study found that boys who drank a protein-rich, nutrient-filled formula for one year grew taller, gained more weight, and built more muscle compared to those who didn’t. The study also showed that the supplement was safe to use and didn’t cause any serious side effects [10]. Supplements like NuBest Tall 10+, designed for children and teenagers aged 10 and older, can help fill nutritional gaps, but they should be combined with proper nutrition, exercise, and sleep. As Brown explains: "Some parents think giving more supplements will guarantee growth, but excessive amounts can cause harm. Supplements should only fill gaps in a well-rounded diet." Always talk to your son’s doctor before starting any supplement to ensure it’s safe and complements his diet to support his growth effectively. 2. Promoting Better Sleep Sleep is one of the most important factors for your son’s growth [11]. During deep sleep, the body produces growth hormones, which are essential for bone and muscle development. Without enough sleep, your son’s growth could slow down. How Much Sleep Does He Need? Studies suggest that boys aged 6-12 years need 9-12 hours of sleep per night, while boys aged 13-18 years need 8-10 hours of sleep per night to allow their bodies to fully rest and grow [11]. Tips for Better Sleep Stick to a schedule: A consistent bedtime helps your son’s body get into a healthy rhythm. Limit screen time before bed: Encourage him to put away phones, tablets, and video games at least an hour before bedtime. Create a relaxing sleep environment: A quiet, dark, and cool room can help him fall asleep faster and stay asleep longer. 3. Encouraging Exercising Exercise is another key part of your son’s development. Regular physical activity helps strengthen bones, stretch muscles, and improve posture, all of which contribute to maximizing height potential. Best Exercises for Growth Yoga: Yoga poses like the cobra stretch and child’s pose help lengthen the spine and improve posture. Stretching Exercises: Simple stretches like toe touches and hanging from a bar can support spinal health and flexibility. 📌 Find our top 6 exercises to increase height in our blog. What About Weightlifting? There’s a common belief that weightlifting stunts growth, but this isn’t true if done safely. Light weightlifting or bodyweight exercises, when supervised, can strengthen muscles and bones. However, heavy lifting or poor technique can lead to injuries, so boys should focus on lighter resistance training until they are older. Posture Is Important Too! Encourage your son to sit and stand up straight, avoid slouching, and strengthen his core muscles. Good posture prevents spinal compression and can help him stand tall. 📌 For more tips on how to get taller, consult our comprehensive guide. Final Thoughts: When Do Boys Stop Growing? Most boys (or people assigned male at birth) stop growing between the ages of 16 and 18 [1, 2, 3], but their final height is shaped by more than just genetics. Proper nutrition, consistent sleep, and regular physical activity all play important roles in helping your son reach his full height potential. As a parent, you can support your son by offering a balanced diet rich in key nutrients, ensuring he gets enough rest each night, and encouraging him to stay active with exercises like swimming, basketball, or yoga. Good posture also matters—it can prevent spinal compression and help him stand tall. If you have concerns about your son’s growth, such as delayed puberty or slow height gain compared to his peers, don’t hesitate to consult a doctor. They can assess his growth patterns and recommend any necessary tests or treatments, like bone age X-rays. For extra support, you might consider height growth supplements like those from NuBest, which are designed to fill any nutritional gaps. Always check with your doctor before starting height growth supplements to make sure they’re safe and right for your child. FAQs About Boys’ Growth When do boys stop growing in height? Most boys stop growing between ages 16 and 18. By then, the growth plates in their bones, which help them grow taller, have closed. This means they won’t get much taller after this point. Can boys grow taller after 18? Yes, it’s rare, but some boys might grow a little taller after 18, especially if they start puberty later than most boys [2, 3]. However, most boys are done growing by this age. What are the signs that puberty is over? The signs that puberty is over are: Height stays the same for over a year. Facial and body hair have fully grown in. The voice has deepened and no longer cracks. The testicles and penis have reached adult size. Doctors can also take an X-ray of the wrist to see if the growth plates have closed, which means the growth has stopped. Is 5'9" short for a guy? No, 5'9" is the average height for men in the U.S., so it’s perfectly normal. Everyone is unique, and being shorter or taller is unlikely to change how successful or capable someone can be. Do boys and girls grow at the same rate? No, boys and girls typically have different growth patterns. Unlike boys, who often grow into their late teens, girls usually stop growing around age 14 or 15. You can read more about when girls stop growing here. Can supplements help boys grow taller? Height growth supplements can help if your son isn’t getting enough nutrients like calcium, vitamin D, or protein from food. However, they won’t make him taller than what his genetics allow. Always check with your doctor before giving supplements. References Gavin, M. L., MD (2019, June). Growth and Your 13- to 18-Year-Old. Kidshealth.org. Retrieved January 27, 2025, from https://kidshealth.org/en/parents/growth-13-to-18.html Tanner, J. M., Whitehouse, R. H., Marubini, E., & Resele, L. F. (1976). 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