I am 13 my penis is about 5 to 4 inches how long will it grow? -
yes its still growing
But if that is not enough for you, you can make it bigger by using natural penis exercises. Check this article for more info on how to make your penis bigger: http://ezinearticles.com/?Did-You-Know-Natural-Penis-Enlargement-Exercises-Can-Give-You-a-Bigger-Penis?-id=2307168
For a 13 year old, I can safely say that your current size is normal. However when you turn 16, you should have at least 7 inches in size.