15 Fascinating Facts About The Penis: From The Average Size To How To Measure Yours Properly

Photo: Wikipedia/Public Domain
one dollar bill used to measure penis size

Most people understand the penis’s role during sex, but for all the praise and attention men often seek when it comes to declaring their penis is bigger and better than any other on the planet, they often know shockingly little about their own anatomy.

Some of the most frequently asked questions about the penis include:

1. What is the average penis size?

2. What is considered a big or small penis?

3. How many men have 7 inches? (And how many have 3, 4, 5, 6, 8, 9, or 10 inches?)

4. How do you measure your penis?

You’d think that understanding all there is to know about their favorite organ would be top of most guys' to-do lists, but unfortunately, that’s not the case for many. And while ignorance can be bliss, knowledge, especially about that oh-so-favored of body parts, is most definitely power.

RELATED: What Women Really Think About The Size Of Your Penis

For instance, take a look at these two little known penis facts:

1. Smoking cigarettes can cause a man's penis to shrink.

Smoking might be one of those "masculine” hobbies some guys think makes them look cool, but researchers at Boston University School of Medicine found that smoking cigarettes can shrink a man's penis up to an entire centimeter.

2. There really are "showers" and "growers."

And researchers found that approximately 74 percent of men fall into the former category. So don't judge a book by its (soft) cover, because at least 26 percent of the time, it might have something quite impressive hidden away that you’re not seeing... at least, not yet.

Considering how important a penis can be to a man’s confidence and his self-esteem, it's unfortunate that so many men believe their capacity for how well they can perform in bed depends almost solely on their penis size.

While this may not seem entirely fair, it turns out that penis size can be a predictor of some matters related to sex, including a woman's ability to have orgasms during penetration. So the idea of being a "size queen" might have some logic to it.

Men and women alike may debate whether or not penis size matters, but while it’s no secret that the penis is there for both baby-making and having a damn good time, there are a lot of things many of us don’t know about phalluses, so prepare yourself to become better informed.

Here are 15 facts about the penis, from the average-sized to how to measure yours properly:

1. There is a proper way to measure a penis, both by length and girth.

The correct way to measure a penis for accurate length is via a measurement referred to by urologists as Bone Pressed Erect Length (BPEL), and Bone Pressed Flaccid Length (BPFL).

To measure penis length: Place a ruler or measuring tape on the top side of the penis, pressing the base of the ruler firmly toward the pubic bone and extending it from there down to the tip of the head.

To measure penis girth: Simply wrap a measuring tape around the widest point of the shaft. Alternatively, you can wrap a string, shoelace, or similar item around the same section, mark where the ends meet, and measure the section of string with a ruler.

RELATED: What Drinking Soda Does To A Man's Penis (According To A Study Guys Should Really Pay Attention To)

2. You can also use a dollar bill to measure a penis size.

There is a clever (if technically less accurate) way to compare a man's penis using a United States dollar bill if you don't want to whip out the measuring tape.

The average-sized penis will be smaller than the width of a dollar bill, which measures 6.14 inches.

If your/his penis comes to the end of the word "One" on the front, it's approximately 5 inches long. If it lands on the first "A" in America, it's about 4 inches.

Photo: Wikipedia/Public Domain

I don't know about you, I may never look at dollar bills the same way again.

3. The average penis size isn't as big as many say it is.

You know you shouldn't care, but since you're probably curious, a study of 1661 men published in the Journal of Sexual Medicine found that the average penis size is smaller than most would probably think.

As self-measured and self-reported, the average penis is 5.6 inches long and 4.8 inches in circumference when erect.

However, new research in a study from 2014, published by the BJU International titled "Am I normal? A systematic review and construction of nomograms for flaccid and erect penis length and circumference in up to 15,521 men" says differently.

The calculations revealed that the average length of a flaccid penis was 9.16 cm, the average length of a flaccid stretched penis was 13.24 cm, and the average erect penis length was 13.12 cm. The girth sizes were 9.31cm for a flaccid penis and 11.66cm for an erect penis.

4. The same penis may actually be bigger or smaller, depending on the 'circumstances.'

Researchers note that the way a man achieves an erection before measuring his penis can affect his results. Most participants in that study "measured their penis while alone, using hand stimulation to become erect."

However, it's also worth mentioning that those who "became aroused through oral sex reported larger penis size on average than those who attained erections through fantasizing."

5. 85% of men have a penis measuring less than 7 inches long.

Only 15 percent of men have penises measuring more than 7 inches long, and only 3 percent measure over 8 inches. But that doesn't mean that huge penises don't exist; they absolutely do.

The smallest recorded human penis measured 0.30 inches (one centimeter), while the largest measured 13.5 inches in length and 6.25 inches in girth. In comparison, the blue whale's penis is the largest in the animal kingdom, averaging 7 feet 10 inches long and about one foot in diameter.

And after his big photo scandal, we now know where Justin Bieber's penis falls on this scale...

6. The penis size women prefer varies.

A study was done in 2015 that practiced the research method of using a selection among 3D models to record data. The participants were shown haptic stimuli to allow assessment of women’s size recall accuracy for the first time, as well as examine their preferences for penis sizes in different relationship contexts found that women have different preferences for different situations.

For a one-night stand, women prefer a slightly larger than average penis sizing at a length of 6.4 inches and a circumference of 5.0 inches.

However, for long-term lovers, women prefer a penis closer to the average size at a length of 6.3 inches and a circumference of 4.8 inches. The study's end result was that "women can accurately recall size and prefer penises only slightly larger than average."

7. Typically, having a small penis is nothing to worry about.

Penis size is only a concern if shorter than 1.4 inches at birth and 3 2/3 inches in adult males. Penises this size are known as micropenises. According to Cleveland Clinic, "Estimates vary, but studies indicate 0.6 percent of men worldwide have the condition."

In such instances, hormone treatment may be prescribed, and surgical reconstruction, known as phalloplasty, is possible. This surgery, however, can be risky, complicated, and painful.

RELATED: Pollution Is Shrinking Human Penises And Making Men Infertile, Warns Scientist

8. Gay men tend to have bigger penises.

Yes, really. Researchers at the Kinsey Institute for Research in Sex, Gender, and Reproduction studied 5,122 men classified as either heterosexual or homosexual over the period from 1938 to 1963.

They found that the majority of homosexual men reported having penises an average of a third of an inch longer than those of heterosexual men.

9. Men can make their penis look bigger than it really is.

The best way to increase the perceived size of your penis size is by losing belly fat.

Makes perfect sense given that, as noted in Vice, "the more excess fat a man accumulates, the more the penis is buried, causing it to effectively lose length."

Unfortunately, if men have a buried penis they could also be struggling with erectile dysfunction/sexual dysfunction, painful intercourse, low self-esteem or depression, urinary tract issues including obstructions, flow issues, urinary incontinence and dribbling, as well as urinary tract infections, skin infections, and skin breakdown.

10. There are devices to help lengthen the male penis.

Another way to increase the size of your penis is by doing specific stretching exercises or devices for it, though the results of this avenue are very minimal and even temporary at times. 

A 2011 study looked at penile extenders, which involved 23 participants using a specific penile extender for 3 months. They found an average gain of 0.7 inches in length.

11. The key to predicting a man's penis size might be found in looking at his fingers.

Researchers at Gachon University in Korea discovered that the difference in length between a man's ring finger and index finger indicated the length of his penis.

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The longer his ring finger is compared to his index finger, the bigger you can expect his penis to be!

12. There are more circumcisions done in the U.S. than in Europe.

The World Health Organization estimates that the overall male circumcision rate in the states is somewhere between 76 and 92 percent.

Most Western European countries, by contrast, have rates less than 20 percent.

13. A penis can break.

Technically, a penis can't "break" because it has no bones, but there is a thing called a penile fracture that can occur. 

Although rare, a penis fracture can occur when there is trauma to an erect penis. This fracture is different from other fractures in the body because, once again, a penis has no bones.

During an erection, the penis is engorged with blood that fills two cylinders (corpora cavernosa). If the erect penis is bent suddenly or forcefully, the trauma can rupture the outer lining of one of the two cylinders (tunica albuginea). This can result in a penis fracture.

The most common cause is during intercourse when the penis slips out of the vagina and is thrust into the pelvic bone. But it can also be caused by aggressive masturbation or by a cultural practice in which the top of an erect penis is forcefully bent to relax an erection, called taqaandan.

14. 'Morning wood' is normal and isn't usually caused by something men dream about.

The actual medical term for morning wood is Nocturnal Penile Tumescence, or NPT for short. Shockingly, yhis is not caused by sexual stimulation from a steamy dream. NPT is actually very common and completely normal. 

It's a result of sleep cycles, combined with healthy nerves and blood flow in the body.

NPT tends to happen when a person is in the REM phase of sleep. Since REM can occur multiple times during an 8-hour sleep cycle, a person may have erections several times during the night but may not be aware of them. 

Often, a person wakes up at the end of a REM sleep cycle, which explains why NPT seems to happen in the morning and thus where it got its name, "morning wood."

15. Scientists spend a lot of time trying to figure out how big a man's penis is without looking at it.

Scientists have tried to find a correlation between the size of men's penises and their shoe size, the size of their noses, thumbs, and even earlobes.

A 1993 study compared the height, foot length, and penis length of 63 Canadian men. Though researchers found a very slight correlation between larger feet and longer penises, they noted that the relationship was so weak that "foot size would not serve as practical estimators of penis length."

Another study of 104 men, published in the British Journal of Urology International in 2002, found no statistically significant correlation between penis length and shoe size.

One study even looked for a connection between flat buttocks and long penises, as a tribe in Nigeria believed this to be the case. However, scientists later determined that the opposite, if anything, is more likely to be true.

In summary, we could simply go back to having men wear tights so their penis size would be more obvious to all, but they would probably stuff their codpieces anyway.

RELATED: Millennial Men Have Huge Penises (If You Believe This Survey)

Linda Sivertsen, aka BookMama, is the author of two New York Times bestselling books, host of the Beautiful Writers Podcast, founder of the Carmel Writing Retreats, and creator of The Boyfriend Log app.