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There’s Only One Correct Way to Measure a Penis

Breaking: Penis length is shorter when people aren't self-reporting.
how to measure penis size
Noah Salzgeber / EyeEm / Getty

If you were paying attention to the headline-grabbing work of pioneering sexologist Alfred Kinsey in the years after World War Two, you would have learned that the average length of an erect penis is around 6.21” while the average girth is 4.85". Because Kinsey and his team were the first to get granular over penis size, and the first to be famous for conducting such titillating research, these figures enjoyed incredible staying power over the subsequent decades. I posit that this 70-year-old data set’s notoriety—along with the ubiquity of porn and the rumored existence of Jared Leto’s formidable trouser schnauzer—may share the responsibility for the prevalence of Short Penis Syndrome or Penile Dysmorphic Disorder.


Thing is, the majority of men who obsess over having a penis they perceive as being too small, are well within the actual average range. That’s not entirely the fault of studies’ limitations, of course, but the repeated publication of skewed data certainly hasn’t helped. Before you dust off your ruler, here's some background on how the figures get wobbly.

The 3,500 participants in Kinsey’s groundbreaking 1948 study were all white, all college aged, and therefore not representative of the general population. Further throwing the data into doubt, Kinsey and his team simply accepted the numbers the undergrads’ gave them as gospel. Incredibly, simply asking a non-representative bunch of guys to just tell you how big their dicks are was still regarded as an acceptable way to gather penis size data throughout the rest of the 20th Century. In the 1990s, Durex commissioned a rather non-representative survey that saw the average erect length and girth had risen to 6.4” and 5.2” respectively.

In 2001, Durex competitor Lifestyles actually had two nurses measure each of 301 hardened volunteers for their study. This was progress of a sort, but again it was mainly US college students being measured so it was not a sample representative of all ethnic backgrounds and ages. Furthermore, this data wasn’t collected in a clinical setting but in a tent behind a Cancun nightclub during spring break. Despite the choice reading material on offer, 25 percent of volunteers were unable to scare up a serviceable boner and, even those who did may have seen their true maximum engorgement impinged by the sheer volume of tequila and Corona-Light sloshing around their sunburned bodies. The erect length and girth was recorded as 5.87” and 4.97” inches respectively.


In 2013, Debby Herbenick—also of the Kinsey Institute—decided to gather self-reported penis measurement data by incentivizing respondents to be more accurate by offering to match them up with a better fitting condom. Exaggerating would of course leave the respondent with a baggy condom or, in the unlikely event of anyone playing down their size, they’d end up in a condom that was too tight. Herbenick’s averages were even lower. She noted an average length of 5.7” and an average circumference of 4.81”. Another interesting finding from the study backed up something that many penis owners and/or users already knew to be true: Even when they are attached to the same person, some erections are more impressive than others and that differences in tumescence could impact measurements to a significant degree.

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In particular, Herbenick saw that respondents who became aroused via oral sex before measuring tended to be larger that those who bootstrapped a stiff one. When talking to LiveScience however, Herbenick was quick to point out that: “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."

While incentivizing a more honest measurement was a canny move by Herbenick, the following year, a team of British researchers decided to do away with self-reported measurements altogether and hand the ruler to the professionals. Researcher David Veale and his team at King’s College, London looked at the penis measurements of 15,521 men taken in a clinical setting, by urologists who all adhered to a standard measuring protocol. When the results came in the average penis size was once again, revised downwards.


Veale reckoned it at 5.16” in length and 4.59” in girth. In the paper, he concedes that “relatively few erect measurements were conducted in a clinical setting.” This, as I’ve postulated in a previous penis-related article, is surely because getting a convincing erection in a clinical setting is easier said than done. As a stand-in for a stiffy, Veale’s study looked at stretched flaccid length which urologists have long noted, is commensurate with erect length.

Veale’s study had limitations of its own but what is has seemed to have done is help codify and standardize the way in which the penis is measured. Bearing in mind that the method by which an erection is attained may affect the measurement, do what you need to work up a maximally engorged subject. Place a transparent plastic ruler on the dorsal (upper side) surface of the penis. Then press the base of the ruler towards the pubic bone, the pubo-penile junction. Really jam it in there as far as you can. You’ll see why in a moment. Whether the penis you’re measuring is circumcised or not, disregard foreskin. That’s like a 5’8” dude using his man bun to get away with saying he’s 5'10”. The reading you are going to take is at the very tip of the glans or head.

This measurement is referred to as Bone Pressed Erect Length (BPEL). BPEL and Bone Pressed Flaccid Length (BPFL)—in which the flaccid penis is stretched—were used in Veale’s study because it prevents the pubic fat pad from diminishing the penis’ true length—hence the pressing in of the ruler. This gelatinous obstruction is no trifle: the more excess fat a man accumulates, the more the penis is buried, causing it to effectively lose length.

Now girth. If you have a measuring tape handy, neat, but all you really need is a piece of string/a shoelace/some al dente pappardelle to wrap around the penis shaft at the widest point then measure with your trusty ruler. If the glans happens to be the widest point, sorry; that doesn’t count.

Having used standard measuring methodology and in light of recent, non-self reported data, many men who obsessively ruminate on the size of the penis should have a less distorted perspective on how they stack up against the mean and, in so doing, may find them less susceptible to Short Penis Syndrome. Regardless of their place in the pecker order, men susceptible to this type of body dysmorphia would do well to remember that length of intercourse and erectile function play a much larger role in partner’s pleasure than size.