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18 Surprising Penis Facts

Kelly Brown MD, MBA

Reviewed by Kelly Brown MD, MBA

Written by Geoffrey Whittaker

Published 10/21/2020

Updated 05/20/2024

Whether you’re seeking facts about the penis for entertainment or have men’s health questions, male genitalia is a fascinating area of study. From weird penis facts and fun penis facts to mythbusters and surprising truths about penile length, there are endless things to learn.

Ahead, 18 interesting facts about the penis, how it works, how it gets hard, penis length, why erectile dysfunction (ED) occurs, who it affects, how it can be treated, and more.

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

We’re not here to say what’s “better.” But a study from 2018 observed 274 patients measuring flaccid length and erect length, and found that there are actually growers and showers. Seventy-four percent were showers, and the rest 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) was pretty small. Further research is needed to crown a king.

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.

Sometimes called nocturnal penile tumescence, these spontaneous erections during sleep happen three to five times a night on average.

Nighttime erections seem to pop up during the rapid eye movement (REM) phase of the sleep cycle, when you’re most likely to dream vividly.

So, no, there’s nothing wrong with getting hard at night — or waking up hard. Frequently rousing without an erection could signal an underlying health issue that’s causing ED. If you haven’t had morning wood at all lately, you might want to mention it to your healthcare provider.

How early do you think you started getting hard? Chances are, 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, they can actually start in the early years of every guy’s life.

Some data even indicates that erections and other signs of sexuality occur in the womb.

Is your penis a muscle? Nope. While “penis-strengthening” products may sound promising, they’re missing a key piece of information: The penis is not a muscle.

Yes, there smooth muscle in the blood vessels that make your penis function, but they operate by dilating to increase blood flow you need to get hard. 

That said, exercising the pelvic floor muscles might help to enhance your sexual performance.

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

One of the harshest facts about the penis is that if it twists or bends too severely, the corpora cavernosa (penile tissue chambers) can burst, with a tear in the tunica albuginea, and cause blood to flow into the other tissue of the penis. This erectile tissue damage can lead to serious pain and swelling.

Reports of “broken” penises are rare, but they can happen.

Repeated injuries to the penis could result in scar tissue, which is thought to contribute to a condition called Peyronie’s disease (a bend or curve in the penis).

Does shoe size predict a man’s penis size? Not really.

A 2002 study (with an admittedly small sample group) found that there was no correlation between men’s penis size and foot size. In other words, a large shoe doesn’t equal a large penis. 

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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 hormones are compromised. We’re not filing this one under “fun facts about penises,” but it’s true.

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

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).

Male circumcision is common in some places like the U.S., but worldwide, it’s not. A majority of American men are circumcised, while being uncircumcised is the norm in most other countries.

Some studies claim health benefits of circumcision, but it’s still a very personal choice.

If you’re measuring your penis, you might be wondering how you compare to the average penis size. Several studies show that the average erect penis size is five to six inches in length.

For instance, a 2014 study published in the Journal of Sexual Medicine sampled 1,661 men. It found an average length of about 5.6 inches. But the participants measured themselves, so the data may not be perfectly accurate.

A separate review published in the Journal of Sex & Marital Therapy looked at used data from over 15,000 men. It reached a slightly lower average of 5.2 inches.

Here’s a fun penis fact for ya: A substantial portion (roughly half) of the overall length is essentially tucked up inside the body, attached to the pubic bone within the pelvis.

This is why some people say the penis is actually twice as long as it looks. (But when we talk about average penis size, we tend to mean what’s visible on the outside.)

Did you know Kellogg’s Corn Flakes® were originally made by a doctor with the goal of deterring men from masturbating?

The ill-advised idea behind this masturbation prevention invention — say that three times fast — was that bland foods wouldn’t stimulate the mind and lead to self-pleasure.

We probably don’t need to tell you that this breakfast cereal doesn’t do much more than provide fortified nutrients and a decent portion of your recommended daily carbs.

People often think of erectile dysfunction as something that mostly affects older men, particularly those in their 50s, 60s, 70s, and beyond. But while ED is more common in the older set, it can (and does) affect men of all ages.

Although younger guys have a lower risk of developing ED, it’s still fairly common. A 2013 study found that one out of every four patients seeking treatment for new onset ED was under 40. 

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Many folks associate male orgasm and ejaculation with erections, but you don’t actually need to be erect to have an orgasm.

Plenty of men with erectile dysfunction can orgasm without being erect or using medications like Viagra® to treat their ED.

Anyone who’s ever used toys like vibrators and prostate stimulators already knows this. If you’re curious, this might be a great time to do some research of your own.

Having ED doesn’t necessarily mean you never get hard. Erectile dysfunction is defined as difficulty developing or maintaining an erection firm enough for satisfactory sexual intercourse.

This means ED could involve getting an erection but failing to keep it during sex — or just struggling to get hard due to performance anxiety. Lots of guys 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.

Ever feel anxious before sex? Feeling nervous about your sexual performance can make it harder to get and maintain erections.

Known as sexual performance anxiety, this can happen when you’re worried about pleasing your partner, self-conscious about how long you last, or having sex with a new person.

In a 2019 review of existing literature, researchers found that sexual performance anxiety may affect as many as 25 percent of men.

Luckily, it’s treatable with ED medications like sildenafil (generic Viagra®) or through things like cognitive behavioral therapy, mindfulness meditation, etc.

Not-so-healthy lifestyle choices like drinking alcohol frequently, smoking cigarettes, and using illicit drugs can contribute to a range of sexual performance issues.

  • Beyond the numerous other health risks associated with cigarettes, smoking can constrict blood vessels, making it harder for blood to flow to the penis. In a 2015 review, researchers found that smokers have an elevated risk of developing ED.

  • Likewise, consuming too much alcohol can affect a man sexually. In a study from 2007, 72 percent of alcohol-dependent male participants had one or more sexual dysfunctions, such as ED, low sexual desire, or premature ejaculation (PE).

FYI: Drinking too much alcohol could also make medications like Viagra® less effective. 

While erectile dysfunction itself isn’t a dangerous health condition, it can be a sign of an underlying medical condition.

ED is common in men with cardiovascular health conditions, including heart disease. It’s also closely associated with type 2 diabetes, which can cause damage to the nerves and blood vessels that supply penile tissues.

Now, this doesn’t necessarily mean you’re unhealthy if you occasionally find it difficult to get and stay hard during sex. However, if it happens often, it might be a sign that something isn’t right.

If you think you might have ED or another condition that causes it, it’s best to see your healthcare provider. A simple medical exam can often help identify the root cause of erectile dysfunction, making it easier to improve your sexual performance and overall health.

Viagra® — the ultra-popular “little blue pill” that came to market in the ‘90s — is the most well-known ED treatment. But it’s definitely not the only medication available for improving sexual performance in men.

Other ED meds can make it easier to get an erection for significantly longer. Cialis®, known as the “weekend pill,” is the longest-lasting.

Cialis contains an active ingredient called tadalafil, which lasts up to 36 hours. This means if you take one tablet on Saturday, it’ll continue working until Sunday night.

Cialis, Levitra® (vardenafil), and newcomer Stendra® (avanafil) also treat ED. These newer meds tend to have longer-lasting effects and fewer side effects than the original little blue pill. 

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Learning facts about the penis can be fun — it can also help you protect your sexual health. That includes the organ itself, the mental health that lets you enjoy intimacy, and the self-confidence to get in the game.

Let’s recap some of our top facts about penises:

  • Penis size isn’t related to shoe size. But the “grower versus shower” argument may be in your corner if your flaccid penile length is a little shorter.

  • Erectile dysfunction doesn’t necessarily mean complete impotence. The condition actually covers a spectrum of problems relating to erections and sexual performance. 

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

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

Want to learn more facts? Our guide to erectile dysfunction walks you through all the causes, symptoms, and treatments.

Not into swallowing pills? Our chewable ED meds hard mints are a convenient way to use prescription medication. We can also help with other sexual performance issues, including premature ejaculation.

24 Sources

  1. Alter GJ, et al. (2011). Aesthetic surgery of the male genitalia. Seminars in plastic surgery.
  2. Alwaal A, et al. (2015). Normal male sexual function: emphasis on orgasm and ejaculation.
  3. Arackal BS, et al. (2007). Prevalence of sexual dysfunction in male subjects with alcohol dependence.
  4. Betjes E. (2014). What is the Nocturnal Penile Tumescence (NPT) test?.
  5. Capogrosso P, et al. (2013). One patient out of four with newly diagnosed erectile dysfunction is a young man--worrisome picture from the everyday clinical practice.
  6. CIALIS (tadalafil) tablets, for oral use. (2017).
  7. Dorey G, et al. (2005). Pelvic floor exercises for erectile dysfunction.
  8. Herbenick D, et al. (2014). Erect penile length and circumference dimensions of 1,661 sexually active men in the United States.
  9. Jalkut M, et al. (2003). Peyronie’s Disease: A Review.
  10. Kim JH, et al (2014). Traumatic penile injury: from circumcision injury to penile amputation.
  11. King BM. (2021). Average-Size Erect Penis: Fiction, Fact, and the Need for Counseling.
  12. Kovac JR, et al. (2015). Effects of cigarette smoking on erectile dysfunction.
  13. Mor Z, et al. (2007). Declining rates in male circumcision amidst increasing evidence of its public health benefit.
  14. National Institute of Diabetes and Digestive and Kidney Diseases (n.d.). Symptoms & causes of erectile dysfunction.
  15. Owings M, et al. Trends in Circumcision for Male Newborns in U.S. Hospitals: 1979–2010.
  16. Panchatsharam PK. (2023). Physiology, Erection.
  17. Parekh A, et al. (2020). Sexual Performance Anxiety.
  18. Sartor O, et al. (2013). Reduced penile size and treatment regret in men with recurrent prostate cancer after surgery, radiotherapy plus androgen deprivation, or radiotherapy alone.
  19. Shah J, et al. (2002). Can shoe size predict penile length?
  20. Shindel AW, et al. (2021). Sexual Dysfunction in Diabetes.
  21. Shirozu H, et al. (1995). Penile tumescence in the human fetus at term--a preliminary report.
  22. Warees WM, et al. (2022). Circumcision.
  23. Wills M. (2019). The Strange Story Behind Your Breakfast Cereal.
  24. Yafi FA, et al. (2016). Erectile dysfunction.
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.

Kelly Brown MD, MBA
Kelly Brown MD, MBA

Dr. Kelly Brown is a board certified Urologist and fellowship trained in Andrology. She is an accomplished men’s health expert with a robust background in healthcare innovation, clinical medicine, and academic research. Dr. Brown was previously Medical Director of a male fertility startup where she lead strategy and design of their digital health platform, an innovative education and telehealth model for delivering expert male fertility care.

She completed her undergraduate studies at University of North Carolina at Chapel Hill (go Heels!) with a Bachelor of Science in Radiologic Science and a Minor in Chemistry. She took a position at University of California Los Angeles as a radiologic technologist in the department of Interventional Cardiology, further solidifying her passion for medicine. She also pursued the unique opportunity to lead departmental design and operational development at the Ronald Reagan UCLA Medical Center, sparking her passion for the business of healthcare.

Dr. Brown then went on to obtain her doctorate in medicine from the prestigious Northwestern University - Feinberg School of Medicine and Masters in Business Administration from Northwestern University - Kellogg School of Management, with a concentration in Healthcare Management. During her surgical residency in Urology at University of California San Francisco, she utilized her research year to focus on innovations in telemedicine and then served as chief resident with significant contributions to clinical quality improvement. Dr. Brown then completed her Andrology Fellowship at Medical College of Wisconsin, furthering her expertise in male fertility, microsurgery, and sexual function.

Her dedication to caring for patients with compassion, understanding, as well as a unique ability to make guys instantly comfortable discussing anything from sex to sperm makes her a renowned clinician. In addition, her passion for innovation in healthcare combined with her business acumen makes her a formidable leader in the field of men’s health.

Dr. Brown is an avid adventurer; summiting Mount Kilimanjaro in Tanzania (twice!) and hiking the incredible Torres del Paine Trek in Patagonia, Chile. She deeply appreciates new challenges and diverse cultures on her travels. She lives in Denver with her husband, two children, and beloved Bernese Mountain Dog. You can find Dr. Brown on LinkedIn for more information.

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