Recently i have been measuring my penis size, i am 18 and still going through puberty, it is 9 inches in length, i am wondering since i am going through a growth spurt, will it grow more, and is there a way to know how much more it can grow?

Small, medium, large: Hard to find good, consistent info on penis sizes, but several doctors on HealthTap have offered opinions. It looks like the average erect one is 5-6 inches, so if one is concerned about being too long, he can talk with his doctor. By age 18, a penis is likely as long as it will get. There's no way to make a penis shorter, so what will be, will be. Doctor can examine, if a patient is worried.