Dr Dick’s response: First, let’s look at information regarding penis size to clarify your concern that your penis might be very small. The length of a non-erect penis usually measures between 8.5cm and 10.5cm (3-4 inches) from tip to base. The average length is about 9.5cm (3.75 inches). Many factors can cause a temporary shrinkage of two inches or more, for instance cold weather or going swimming, so you needn’t worry if you happen to fall short of the average figure. Interestingly, most penises are very much the same size when erect. A guy whose non-erect penis is smallish will usually achieve about a 100 % increase in length during sexual excitement. A guy whose non-erect penis is already quite large will probably manage about a 75 % increase. This means the great majority of penises measure between 15cm and 18cm (6-7 inches) when erect, with the average figure being about 16.5cm (6.5 inches). The average width of a flaccid penis is 3.1cm (1.25 inches) and 4cm (1.6 inches) when erect.
Medical articles and research shows that it is quite difficult to enlarge penis size. You could try a “penis pump” which is said to also enhance sexual performance, but conflicting debates exist whether it really increases penis size. User instructions need to be followed carefully as the penis pump might cause damage to the penis (burst blood veins).