How big should a 20 year old penis be when it is erect? -
At 20, most guys penises are fully grown, and if they are still growing, it won-t be much more, since growth slows down towards the end of puberty.
The average size for an adult is just under 6 inches, and 80% of adult penises are between 5 and 6.5 inched when fully erect.
I understand that asian guys tend to be a bit smaller, and africans a bit bigger.
