The body is also pretty amazing in that the shorter a penis is when limp, the more it grows when it is erect! So two guys with very different sized penises when limp might actually be the same size when erect.
There are a bunch of places with varying information, but all agree that at thirteen you probably have not reached the size your penis will eventually be. The average size for a fully grown man's erect penis is 5-6 inches (taken from a few scientific research studies). This means that your penis is actually a good deal larger than could be expected at your age.
This doesn't mean you'll grow up to have hugely endowed; it could mean that as your penis is this size now, you may not grow as much in later years. Or, of course, you could. Your body is hugely unique, and the sooner you appreciate what it has to offer, the happier you'll be.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.