It's not the sort of thing many men would own up to. But hands up who's worried about the size of their penis. Well, don't worry. You may not be big - you're probably just about average.
And I thought I already had every anxiety under the sun… Now it seems I can add Body Dysmorphic Disorder to my repertoire, because there is no way I will measure up (as soon as I get home) to what a team of British researchers says is a normal penis size.
The team at King's College London - led by David Veale - analyzed data from 20 existing studies that involved more than 15,500 men, to come up with "average" sizes for flaccid and erect penises.
"We tried to choose the ones that fulfilled particular inclusion criteria of quality and tried to get a bigger picture by combining them all," Veale told DW. Their meta-analysis has been published in the British Journal of Urology International.
While the studies had been conducted internationally - in Nigeria, Turkey, Jordan, France, Korea, India, Germany, United States, Iran and Bulgaria, among other countries - they remain far from conclusive or fully reliable.
No standards for average size
One reason is their lack of standard methodology.
Study participants ranged from 17 to 91 years of age and came from different backgrounds, or "populations." They may have been medical students in Nigeria, military volunteers in Turkey, circumcision patients in Tanzania, people at a sexual dysfunction clinic in Kerala, or plain old volunteers in Germany.
Then there are the "reported measurement details." Some men were measured at room temperature, some under anesthesia, some "lying down, legs slightly abducted" and others were taken "standing with the penis held parallel to the floor."
In some cases, examiners used measuring tape. In Egypt, they used a "rigid ruler" instead (not, we understand, a political reference).
Despite these variations in the data, the UK researchers say they were able to determine average sizes, and they hope their release will "reassure the majority of men."
The average length for a flaccid penis appears to be 9.16 centimeters (3.606 inches) and erect it appears to be 13.12 cm (5.165 in). The average circumference of a flaccid penis is 9.31 cm (3.665 in), and erect is 11.66 cm (4.590 in).
But how significant is this for science?
"Not that much," laughs Veale. "It is a combination of 20 previous studies to try to make a more accurate picture."
A first step to help
But the more we know about the size of men's penises, and the more we are able to refute bogus concepts - such as race, or the age-old correlation between the size of a man's feet and the size of his "member" - the more we may arrive at practical applications, such as designing more efficient condoms.
Doctors may also have a better chance of treating men with Body Dysmorphic Disorder (BDD).
"Some men have a big discrepancy between what they think they are, what they believe they actually are, and what they believe they should be," says Veale.
Risk factors associated with BDD include difficult relationships in your formative years.
"You may have been teased by your peers," says Veale, "you may have had specific teasing about your genitalia from a partner. And all these things can make you more vulnerable, as well as genetic factors. Trying to prevent it from happening is the key."
Veale and his team have created new nomograms (as pictured here) from the pre-existing data.
They hope the nomograms will be used in clinics so as to reassure men who seek help "that they are in the normal range and they are not abnormally small."
"It's going to help the majority of people who are worried, but it's not - by itself - going to help those people with more severe Body Dysmorphic Disorder," says Veale.
As for this writer, I'm not taking any chances: I've got my tape measure - and a rigid ruler - at the ready.