Boys typically stop growing in height once they have finished puberty, which usually occurs between the ages of 16 and 18. Most boys reach their adult height by around age 16, but some may continue to grow slightly until about age 18 or even into their early 20s in rare cases
. The reason growth stops is that the growth plates-areas of cartilage near the ends of long bones-gradually harden and fuse into bone, preventing further lengthening of the bones
. This fusion generally happens by age 18 but can vary depending on when puberty starts and how long it lasts. Puberty itself typically begins between ages 8 and 14, with boys often starting around age 12. The fastest growth spurt usually occurs 1 to 2 years after puberty begins, and puberty lasts about 2 to 5 years. Boys who start puberty later may grow more rapidly to catch up and still reach a similar adult height as early maturers
. In summary:
- Most boys stop growing in height by age 16.
- Full physical maturity, including reaching final height, is usually by age 18.
- Some boys may grow slightly into their early 20s, but this is uncommon.
- Growth stops when growth plates fuse after puberty ends.
Muscle development and other physical changes can continue well into the 20s, but height growth essentially ends after the late teens
