Men Can't Be Trusted To Measure Their Own Penis Size, Study Finds

"In the most extreme case, the self-reported erect penis size (9,000 cm) [295 feet] was 50 times larger than the penis size of an adult elephant, which has the largest penis of any land animal."

James Felton

James Felton

James Felton

James Felton

Senior Staff Writer

James is a published author with four pop-history and science books to his name. He specializes in history, strange science, and anything out of the ordinary.

Senior Staff Writer

A man measuring a banana, which is tucked into his pants.

Using a banana is definitely cheating. Image credit: TeodorLazarev/

There is a big problem with penis research – or, at least, men will tell you it's big. If you ask men their penis size, they will lie and tell you it is bigger than it actually is. A new study has looked at just how much men lie about their penis size to researchers, and whether they would provide more accurate data about this and other masculinity markers if they were paid better for their participation.

To conduct the research, the team from the University of Agder, Noway, and the Swedish University of Agricultural Sciences asked men to self-report their penis size, height, and how athletic they were compared to the population. The participants were split into two groups, separated only by how much they were paid to take part in the experiment, either around $5 or $22.


The team excluded any big outliers in terms of claims.

"In the most extreme case, the self-reported erect penis size (9,000 cm) [295 feet] was 50 times larger than the penis size of an adult elephant, which has the largest penis of any land animal," the team notes in the study.

With these outliers – likely indicating non-engagement with the study – excluded, the team found that as a group the men's self-reported measures were above the population mean and midpoint, except for estimations of their weight. 

"However, the most extreme deviance from the Danish mean," the team explained, "was found for erect penis size, in which participants’ self-reported size (M = 18.02 cm, SD = 3.72) was 21.1 percent larger than the stated Danish mean of 14.88 cm [5.86 inches]."


Both groups estimated their penis size to be "dramatically" above the norm, but the team found that those in the better-paid group exaggerated less about their measurements, suggesting that paying participants better could increase the validity of self-reported penis research.

"The group receiving the smaller monetary reward self-reported a greater erect penis size than the group receiving the larger monetary reward," the team explained. "The same pattern of results was found for flaccid penis size."

However, though the misreporting of member size was decreased by paying more to participants, the group's penis size was still significantly above the average.

"These results indicate that, when interested in bodily variables important to men’s self-view and identity, such variables should not be done through self-report," the team concluded. "Especially not if they concern private bodily measures linked to masculinity (i.e., penis size)."


"Our results suggest that private data related to bodily cues of masculinity can only be reliably collected in the lab," they added, "where conditions can be fully controlled."

The study is published in Frontiers in Psychology.

[H/T: PsyPost]


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