There is no set answer to this one and penile growth can in some individuals continue on well into their 20's. As the son of an MD researching this became a sort of hobby to break the boredom when I was in college.

The one thing that is definitely the case is that the younger you are the more quickly you will respond to and the more effective various well thought out enlargement efforts can be. During the time you are still growing the various ligament structures inside your penis still remain stretch-able. As you age these become more and more resiliant to any efforts to stretch them.

Maybe one of the others reading this will remember the name of the African I believe tribe that ties weights to the genitals of young males to stretch the genitals of these young men. What they do often does nothing for and in fact is a problem because they do too much too fast and it destroys the ability of the "stretch-ee" to ever have a meaningful erection.

The fact is that they do this at a young age where the stretching is easy. We "older guys" from civilized society usually start trying to stretch things in a manner of speaking that is somewhat like "closing the stall gate after the horse has already escaped".

When you are in your 20's the one thing I will drum into all of you is to go in to your MD and make your testosterone level with both a serum and free-floating testosterone level test a part of your documented medical record.

You want to have that level documented somewhere at the highest possible levels. This will allow YOU the choice for male hormone replacement 20 years or more down the road. The current rules of the FDA on male hormone replacement basically are you can replace it if you can document that it was higher in that individual and that it has fallen over age and time.

If you have no documentation of higher levels you can not institute male hormone replacement until the levels are indeed very low without raising attention in a negative manner for the MD in question.