"I find sex painful with a man bigger than 10cm and in the past have had to resort to oral but miss that close intimacy of sex," Z said. "I can hardly ask a new potential partner when dating about their size, and that may be exaggerated anyway!"
A male user, 36, said dating had previously been "very complicated" for him.
"A lot of my mates found their partners from friends of friends or via work.
"Imagine the situation when one of these relationships fails, she's likely to mention my size to her friends and then gossip spreads."
He said it was better to date online where "everyone knows in advance".
"There's pressure on all genders to conform to ideals set by TV, film and even porn. The adult entertainment industry only casts males with well over average sized penises," David Minns, the founder of Dinky One said in a statement.
"In addition, adverts on major porn sites advertise dubious products to increase penis size. All of this makes a man already insecure about his size even more self conscious.
"Some men are big, some average and some below average. Dinky One lets smaller men date people outside their circle of friends with the safety that everyone using the site is fully aware. Members can focus on shared interests and get on with dating."
News.com.au contacted Dinky One for a comment.