Not everyone can boast 9 and 3/4.
Dobby -- 1.3 inches

Absolutely tiny little thing, like a raisin. From some distances, barely even visible.
Warner Bros.
Voldemort -- 2.2 inches

Some attribute Lord Voldemort's capacity for profound evil to his never having known a mother's love. The majority attribute it to his dinky dong.
Warner Bros.
Harry Potter -- 2.2 inches

Harry has a penis precisely the same size as Lord Voldemort's, and, of course, part of Harry's soul lay within Voldemort's penis, and vice versa. Neither could reproduce while the other penis was alive.
Warner Bros.

Ranking "Harry Potter" Characters By Penis Size