A study published last week in the Journal of Sexual Medicine found that the average American man's penis size when erect is 5.6 inches long, while the average erect penis circumference is 4.8 inches. Researchers found that the way a man becomes erect (whether by self-stimulation or other means) can affect erect penis dimensions.
Dr. Debby Herbenick headed the research that took place at Indiana University. The study sought to assess men's erect penile dimensions and "to explore associations between men's erect penile dimensions, their method of measurement, and their demographics."
Penis Size And Arousal Method
"Although many men may wish their penis were larger and may expend significant effort toward penile enlargement, this does not necessarily mean that men overreport their penile size to researchers," the researchers wrote.
Researchers used data from 1,661 sexually active men who reported their penis length and girth for the purpose of getting customized condoms to fit their erect penises. They used this data in hopes that men would be more likely to be truthful in self-reporting their actual penis size when it was associated with a personal commodity, like a custom condom.
According to LiveScience, the study found that men using certain methods to achieve an erection were larger on average than others. Men who became aroused using oral sex reported a larger penis size than those who became aroused through self-stimulation.
"We don't know if that means that when men have oral sex that it's more arousing and they get a bigger erection, or means that men who have bigger penises could be getting more oral sex in the first place," Herbenick told LiveScience.
The smallest erect penis in the study was about 1.6 inches long. The largest penis in the study was 10.3 inches long.
Factors That Contribute To Penis Size
LiveScience reports that past studies found characteristics like race and sexual orientation are not usually good indicators of size, but the proportions of one's body may be. Many men have penises that are in direct proportion to their height. But even that theory doesn't hold true to everyone.
But one theory that has picked up quite a few supporters in recent years is that women's preferences contribute to penis size. Here's how it works: Woman sees man with large penis. She's attracted to him, and then they get married and have sex. When they reproduce, their sons are likely to have large penises, too. That's how researchers have previously explained why humans have relatively large genitals compared to their body size.
Does size really matter?
Well, yes. Penis size does matter. But, it doesn't seem to matter quite as much as some people think.
A 2012 study found that women who have frequent vaginal orgasms are more likely to say that they prefer men with larger penises. On the other hand, women who more frequently have clitoral orgasms may not be as picky.
"This might be due at least in part to greater ability of a longer penis to stimulate the entire length of the vagina, and the cervix," said researcher Stuart Brody.
Why don't researchers study vagina characteristics?
Herbenick said that it would be interesting to see what the same type of research would find about women's vaginas. People rarely inquire about vagina size, while the size of men's genitals are rather commonly discussed.
"It would be good for women to have good data to show, 'Hey, there's a lot of diversity for women's genitals, just like there are for men's," Herbenick said.
Source: Herbenick D, Reece M, Schick V, Sanders SA. Erect Penile Length and Circumference Dimensions of 1,661 Sexually Active Men in the United States. Journal of Sexual Medicine. 2013.