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

How many men have 7 inches or more?

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

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 few facts about their own anatomy.

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

What is the average penis size?

What is considered a big or small penis?


How many men have 7 inches (And how many have 3, 4, 5, 6, 8, 9, or 10 inches?) and it that a good size?

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: If He Has One Of These 4 Penis Types, Your Sex Will Be Amazing


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 size 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 measurements referred to by urologists as bone-pressed (BP) and non-bone pressed (NBP).

To measure penis length using the BP method: 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.


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.

how to measure your penis with a dollar billPhoto: Wikipedia/Public Domain


I don't know about you, but 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 2013 study of 1661 men in the U.S. 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.

A 2014 study of 15,521 men in the UK published in the British Journal of Urology International gets even more specifc.

Their calculations revealed that the average length of a flaccid penis is 3.60 inches, the average length of a flaccid penis when stretched is 5.21 inches, and the average length of an erect penis is 5.165 inches. As for girth, their findings revealed an average circumference of 3.7 inches when flaccid and 4.6 inches when erect, so all-in-all, not so far off.


So if you're wondered what is a considered a big penis, while answers are subjective, logic holds any penis measuring above average — so 6, 7, 8 or 9 inches — could reasonably be called big.

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 the US study mentioned above "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. How many men have a penis measuring 7 inches or more?

Only 15% of men have penises measuring more than 7 inches long, only 3% measure over 8 inches, and only 7 in 1000 guys (0.7%) have a 9-inch penis. But while 85% of men have a penis that measures less than 7 inches in length, 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.

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.


In a 2015 study, researchers at UCLA used 3D models and haptic stimuli to assess women's preferences in relation to penis size.

Their findings state that for the purposes of a one-night stand, women prefer a slightly larger than average penis, indicating a preference for a penis measuring 6.4 inches in length and 5.0 inches in circumference.

However, in the content of a long-term relationship, women preferred a penis closer to the average size, at 6.3 inches in length and 4.8 inches in circumference.

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

7. Typically, small penises are not considered to be a medical concern.

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.

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. You can make your penis look bigger than it 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."

10. 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.

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.


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

12. A penis can be fractured.

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

Although rare, a penis fracture can occur when there is trauma to an erect penis. This kind of 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, resulting in a penis fracture.

The most common cause is a penis slipping out of a vagina during intercourse, then thrusting into the woman's pelvic bone.

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

And researchers found that approximately 74% 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.


14. "Morning wood" is normal and isn't usually caused by sexy dreams.

The actual medical term for a morning erection is nocturnal penile tumescence, or NPT for short.

This isn't caused by sexual stimulation from a steamy dream. NPT is common and completely normal, and usually isn't caused by steamy dreams, but happens as a result of sleep cycles, healthy nerves and blood flow.

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 the size of their shoes/feet, 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.