16 Surprising Penis Facts

Kristin Hall, FNP

Reviewed by Kristin Hall, FNP

Written by Geoffrey Whittaker

Published 10/21/2020

Updated 08/17/2023

Your penis is a character of many talents — a conundrum wrapped in a riddle (and possibly, also foreskin).

We guys Google facts about our wedding tackle for many reasons, from health concerns to boredom. Worried about erectile dysfunction? You’re not alone. Erectile dysfunction, or ED, is common and can affect men of all ages and backgrounds. 

Want to know if that shoe size legend is anything more than myth? We’ve got you.

Below, we’ve listed 16 surprising facts about the penis, how it works, how it gets hard, how and why erectile dysfunction occurs, who it affects, how it can be treated and more.

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The Growers vs Showers Phenomenon Is Real

The argument over whether it’s better to be a grower (smaller penis that gets bigger when erect) or a shower (penis that is already reasonably big when flaccid and doesn’t enlarge all that much when erect) is as old as time.

Surprisingly, it turns out the contrast between showers and growers may actually have some real science behind it, beyond what some dude said about the water being cold in the pool.

A study from 2018 observed 274 patients via penile duplex Doppler ultrasound and found that there are, in fact, growers and showers. Seventy-four percent of patients were “showers,” while 26 percent were growers. 

Is that enough to lock the grower-shower debate in as fact? Not exactly. This study (and most of what we found before it) were pretty small — further research is needed to crown a king.

Men Get Erections While Sleeping

Ever wonder why you often wake up with an erection? Morning wood, as it’s known, is an extremely common phenomenon. It’s also an excellent overall indicator of sexual health. 

Also known as nocturnal penile tumescence, these spontaneous erections during sleep happen,  on average, three to five times per night of sleep, with each lasting for about half an hour. Of course, the number of erections per day (or night) you get can vary thanks to a lot of different factors.

Nighttime erections appear to occur during the rapid eye movement (REM) phase of the sleep cycle, which is when you’re most likely to dream vividly. 

So no, there’s nothing wrong with getting hard at night, or waking up hard. In fact, frequently waking up without an erection could signal an underlying health issue that’s causing ED — and you might want to mention it to your healthcare provider. 

Erections Start Early in Life, Sometimes Before Birth

How early do you think you started getting hard? Chances are that you probably don’t remember your first erection — you might not have even been born.

While most of us associate erections with adolescence and adulthood, erections actually start in the early years of every guy’s life.

In fact, there’s some data out there that indicates erections and other signs of sexuality can even occur in utero. 

Cool factoid as a conversation starter? Maybe. But probably not the one to lead with at family dinner.

Contrary to Popular Belief, The Penis Isn’t a Muscle

While the “strengthen your penis” products may sound promising, they’re missing a key piece of information: the penis is not a muscle.

Yes, there are muscles that make your penis function, but they operate more like valves for the blood flow you need to get hard. 

With this said, there are some exercises for the pelvic floor muscles that might help to enhance your sexual performance. 

The penis is made up of sponge-like chambers called the corpora cavernosa, which, when you feel aroused, gradually fill up with blood. As the corpora cavernosa fills with blood, the increase in pressure prevents blood from flowing away, giving you an erection.

This is why healthy blood flow is so essential for erectile health. The easier it is for blood to flow into the corpora cavernosa, the easier it will be to get an erection when you’re aroused. 

Yes, You Can Break Your Penis

Your penis isn’t a muscle. It’s also not a bone. But penile fractures? Sadly they’re still a risk you’ve got to be wary of.

If your penis is twisted or bends too harshly, it’s possible for the corpora cavernosa to burst and cause blood to flow into the other tissue of the penis. This erectile tissue damage can lead to serious pain and swelling of the penis. 

Reports of “broken” penises are fairly rare, although they are known to happen

Repeated injuries to the penis may result in the development of scar tissue, which is believed to contribute to a condition called Peyronie's disease. 

Shoe Size Doesn’t Correlate to Penis Size

Does shoe size predict penis size? If it did, buying shoes would certainly be more interesting. Unfortunately for the guys who might brag about their high slipper sizes, their claims don’t transfer up the sizing chain.

A 2002 study (though with an admittedly small sample group) found that there was no correlation between penis size and foot size, and that a large shoe does not equal a large penis.

But if someone you’re attracted to believes you’re going to be well-endowed because you’re sporting size 13 sneakers, it’s not up to you to correct her.

Penis Shrinkage is Real

As for penis shrinkage, it’s real too, although it’s not exactly coming from that cold pool or a lack of hot water in the shower. 

Treatments for prostate cancer and other conditions can, over time, lead to shrinkage of the penis, especially when your hormones are compromised. 

Atrophy and other causes of a permanently flaccid penis like a spinal cord injury can also lead to shrinkage. This is sometimes avoidable with proper treatment and hormone replacement.

Most Men Aren’t Circumcised

Circumcision, as you may or may not know, is the process of removing the foreskin from the male organ. This exposes the glans (head of the penis) and, according to absolutely no real science, makes it look bigger(ish).

Being circumcised is fairly common in some places, but worldwide, it’s not something you see every day. For most of the 20th century, it’s been common in the U.S. for men to be circumcised, while being uncircumcised is far more common in the rest of the world.

Some studies claim that there’s increasing evidence of the health benefits of circumcision, but if you’re not already circumcised, that’s a decision we’ll let you make on your own.

The Average Erect Penis is 5.2 to 5.6 Inches

No guy really cares to measure penis size unless they have an idea of how they measure up to the average penis size. Well, pick up the ruler, because here’s your answer.

While there’s no precise average penis size for men, several studies have attempted to answer this question, with most showing that the average erect penis size is somewhere between five and six inches in length (which is small, right? Or huge?). 

A 2014 study published in the Journal of Sexual Medicine, which sampled 1,661 men, found an average length of 14.15cm, or about 5.6 inches. With this said, this study relied on the men to measure themselves, meaning the data may not be perfectly accurate. 

A separate review published in the Journal of Sex & Marital Therapy, which used data from more than 15,000 men, reached a slightly lower average of 13.24cm, or about 5.2 inches.

In other words, the average guy isn’t porn star-big — and you don’t need to be. Plus, most women don’t find penis size all that important anyway. 

Erectile Dysfunction (ED) Affects Young Men Too

Erectile dysfunction is relatively common. As many as 30 million American men may be affected by ED, which means that you could be in line for coffee right now with a handful of guys who struggle to get it up. 

Most people think of erectile dysfunction as something that mostly affects older men, particularly men in their 50s, 60s, 70s and beyond. But while ED is more common in older men than in younger men, it can and does affect men of all ages.

Although younger men are at a lower risk of developing ED, it’s still fairly common. A study first published in 2013, which used data from more than 400 patients, noted that one patient out of every four seeking treatment for new onset ED was under the age of forty. 

In short, you’re more likely to get ED the older you get, but youth is no protection. 

Why this happens has to do with the causes of ED. Erectile dysfunction can be physical or psychological. When it’s physical, factors like high blood pressure or heart disease are often the culprits. 

However, psychological ED may be caused by everything from performance anxiety to watching (and masturbating to) too much porn. This phenomenon, referred to as porn-induced ED, hasn’t been studied much. However, there’s some scientific evidence linking porn usage to sexual dysfunction. 

If you’ve been watching porn more frequently and find it harder than normal to get an erection, this could be worth discussing with a healthcare professional.

You Don’t Need to Have an Erection to Orgasm

Although most people associate male orgasm and ejaculation with erections, you don’t actually need to be erect to have an orgasm.

In fact, many men with ED can orgasm without being erect or using medications like Viagra® to treat their ED. 

Anyone who’s ever engaged in the use of toys like vibrators and prostate stimulators already knows this — and if you’re curious, this might be a great time to do some research of your own.

Having ED Doesn’t Mean You Can’t Ever Get Hard

Although most people associate the term “erectile dysfunction” with the inability to get any kind of erection at all, this isn’t technically correct — at least not all the time. 

Erectile dysfunction is defined as difficulty developing or maintaining an erection firm enough for satisfactory sexual intercourse. 

This means that ED could involve getting an erection but failing to maintain it during sex, or just having difficulty getting an erection due to performance anxiety. Many men with ED might find it easy to get an erection in some circumstances, but not in others. 

Some men, for example, might get ED when they’re feeling stressed, but have no issues getting an erection when they’re in the right mood. 

Sexual Performance Anxiety is Common, And it Can Take a Toll on Your Erections

Ever feel anxious before sex? Feeling anxious about your sexual performance can make it far more difficult to get and maintain an erection, even if you’re already excited, totally in the mood and ready to go. 

Commonly known as sexual performance anxiety, this form of anxiety tends to occur when you feel concerned about your sexual performance, worried about how you look or just stressed in general. 

In a 2019 review of existing literature on sexual performance anxiety (from 2000 to 2018), researchers found that sexual performance anxiety may affect as many as 25 percent of men.

Luckily, sexual performance anxiety is treatable, either through the use of ED medications like sildenafil (generic Viagra®), or through things like cognitive behavioral therapy, mindfulness meditation, etc.

Alcohol, Smoking and Drug Use Can All Contribute to ED

We hate (okay, not really) to be the official voice of men’s health and good habits, but let’s get real for a second: you probably already know that lifestyle choices like drinking alcohol frequently, smoking cigarettes or using illicit drugs can all contribute to a range of sexual performance issues. Having whiskey dick — or… umm… cigarette dick? — isn’t what you want to be actively working toward.

Let’s start with the connection between smoking and ED. Beyond the numerous other health risks associated with cigarettes, smoking can constrict your blood vessels, making it harder for blood to flow to the penis. In a 2015 review of smoking and erectile dysfunction, researchers found that smokers have an elevated risk of developing ED. 

Likewise, consuming too much alcohol can affect a man sexually. Excessive consumption of alcohol is closely linked to sexual dysfunction, with a study from 2007 indicating that 72 percent of alcohol-dependent male participants had one or more sexual dysfunctions, such as erectile dysfunction, low sexual desire or premature ejaculation. 

Drinking too much alcohol could also make medications like Viagra less effective, which is a bummer if you paid for that and then drank away its effectiveness. 

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ED Can Signal a More Serious Health Issue

And while we’re being downers, let’s address the most important: while erectile dysfunction itself isn’t a dangerous health condition, it can often be a sign that you may have an underlying medical condition.

Erectile dysfunction is common in men with cardiovascular health conditions. For example ED is strongly linked with heart disease, with several studies indicating that men who have ED tend to have an elevated risk of heart disease.

ED is also closely associated with type 2 diabetes, which can cause damage to the nerves and blood vessels that supply the tissue of the penis.

Now, this doesn’t necessarily mean that you’re unhealthy if you occasionally find it difficult to get and stay hard during sex. However, if you find it difficult to get an erection at all, even when you feel relaxed and comfortable, it might be a sign that something isn’t right.

In either case, it’s best to see your healthcare provider. A simple medical exam can often help you to identify the root cause of erectile dysfunction, making it easier to improve your sexual performance and your overall health. 

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Some ED Medications Last For an Entire Weekend

Think of medication for treating ED and you probably think of Viagra (or sildenafil, its generic version)  — the ultra-popular “little blue pill” that came onto the market in the 1990s. While Viagra is the most well-known treatment for erectile dysfunction, it’s definitely not the only medication available for improving sexual performance in men.

Other ED medications can make it easier to get an erection for significantly longer. Cialis®, known as the “weekend pill,” is the longest-lasting of the ED medications. It contains an active ingredient called tadalafil, which lasts for up to 36 hours. This means that if you take one tablet on a Saturday, it will continue working until well into the night on Sunday. 

Cialis, Levitra® (which contains vardenafil) and Stendra® (the newest ED medication on the market) also treat ED,often with longer-lasting effects and fewer side effects than the original little blue pill. 

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Penis Facts: The Bigger Picture

Penis facts are fun and informative, but they can also help you, you know, protect your sexual health. That includes your penis itself, the mental health that lets you enjoy intimacy and the self-confidence you need to get in the game in the first place. So let’s recap some of our top facts about penises.

  • Your penis size isn’t related to shoe size, but the grower and shower argument may be in your corner if your flaccid penis length is a little shorter.

  • The term “erectile dysfunction” doesn’t only refer to complete impotence — it actually covers a spectrum of different problems related to erections and sexual performance. 

  • It’s normal and quite common to sometimes have trouble getting an erection, especially if you’re tired, intoxicated, stressed or just not in the mood for sex. Regular erections with occasional issues doesn’t suggest a disorder.

  • Erectile dysfunction is extremely common. It’s also highly treatable with a variety of erectile dysfunction treatments.

Want to learn more facts? We can help. Our guide to the treatment options currently available for ED lists everything you need to know about taking action to treat ED and improve your sexual performance — our chewable ED meds hard mints are a convenient way to get and use medication.

We can also help with other sexual performance issues, including premature ejaculation treatments and online therapy for stress and ED

If you don’t feel like you’re bringing your best game to the bedroom right now, we can help. That’s a fact.

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Editorial Standards

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Kristin Hall, FNP

Kristin Hall is a board-certified Family Nurse Practitioner with decades of experience in clinical practice and leadership. 

She has an extensive background in Family Medicine as both a front-line healthcare provider and clinical leader through her work as a primary care provider, retail health clinician and as Principal Investigator with the NIH

Certified through the American Nurses Credentialing Center, she brings her expertise in Family Medicine into your home by helping people improve their health and actively participate in their own healthcare. 

Kristin is a St. Louis native and earned her master’s degree in Nursing from St. Louis University, and is also a member of the American Academy of Nurse Practitioners. You can find Kristin on LinkedIn for more information.

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