Is 7 inch good for a 16 year old (and did I measure correctly?)?

Okay so here's how I measured. I got a full erection, got a ruler and then stuck my penis straight forward, perpendicularly to my body. And put the ruler on top of my penis right over the skin (not pushing unto the skin) and I measured from the base (where my pubic hair is) straight up to the tip. Is that correct? And I got spot on at 7 inches. I'm skinny and I really don't know if my penis follows suit but I think it might be a little skinny as well, I haven't measured the circumference. But for a 16 year old is that good or bad?