You might've noticed that your penis changes size throughout the day, and that not every erection is equal. But why is that? The biggest thing to remember is that your dick is a vascular organ that is powered by blood pressure. It responds to the state of your body; so if you take care of yourself you're taking care of your cock. When your body isn't getting what it needs, it'll put less effort into your reproductive systems as it instead focuses on keeping itself alive. Given all the good stuff and minimal bad stuff, you can achieve your peak size on a more regular basis.
Let's dig into all the things that can impact how big your penis hangs and how large your boners are…
Hydration
Proper water intake is hugely important for all functions of your body. If you're not properly hydrated, inessential activities like penile blood flow will be curtailed. With less blood flowing into your genitals, both your soft size and hard size will suffer.
Stress
When you're stressed, your body prepares itself for fight-or-flight actions. One of the biggest physiological impacts comes from the production of the hormone cortisol, which diverts blood flow to important muscle groups like your legs and away from things you won't need to get yourself out of a fight with a sabertooth tiger, like a large penis. That's why when you're stressed out you'll likely find that your penis and testicles retract closer to your body — both to protect them and to use that blood elsewhere.
Additionally, the mental pressures of stress can make it difficult to attain and maintain an erection. If your head just isn't in it then you'll have trouble getting your head into it.
Injury
The penis is a blood sponge wrapped in a skin balloon. Which despite the "boner" nickname and rock-hard feel, when fully engorged it can be somewhat fragile. When fully erect your penile tissue are under significant tension and it doesn't take much to rupture an internal membrane.
The problem is that when healing the human body has a tendency to develop scar tissue. And when inside the penis that scar tissue can limit the expansion potential of the erectile tissues. This can lead to reduced erection size or curvature towards the side of the injury.
So be careful during sex; a hard impact on your penis can hurt in the moment and lead to a lifetime of issues.
Alcohol
"Whiskey Dick" is a real thing. Alcohol is a depressant, in that it works to reduce signals sent through the nervous system. This has the effect of making it harder to get hard, no matter how much your brain wants it to. If the signals aren't going out, then the arteries and veins that are vital to erection quality just aren't going to do what they need to do. Alcohol also acts as a vasodilator, opening up blood vessels — which is the opposite of what you want for the veins that control the flow of blood out of the penis.
On the flip side, Whiskey Dick also tends to increase flaccid size. The same vasodilator effect that makes it difficult to keep the blood pressure up in the penis also allows more blood to flow in overall, often resulting in a noticeable increase to your softie size.
Temperature
One of the human body's tools to fighting cold is to divert blood from the extremities to the torso, keeping those internal organs warm and operating well. So come winter time, as your fingers and toes feel colder all the time you can also expect that at least your flaccid dick will retreat somewhat due to the reduced blood supply. Erection quality typically doesn't suffer with the colder weather. It's also common for testicles to hang closer to the body during the cold in an effort to maintain optimal temperature for sperm production.
In the warmer summer, the opposite happens — "summer dick". More blood is pumped into your extremities, penis included, leading to an increased flaccid size.
Cardiovascular health
As mentioned a few times already, the penis is a vascular organ; a blood sponge in a skin balloon. As such, it's very responsive to the state of your cardiovascular health. The better shape you're in, the better and more consistent your erection quality will be. If you're less fit, your erection quality and size will suffer.
Nicotine
Whether ingested via smoking or dip or gum or vaping, nicotine has a deleterious effect on erection strength and size. Nicotine causes blood vessels throughout the body to contract, limiting the available blood supply necessary to establish and maintain an erection.
The good news is that while there can be a permanent impact on your cardiovascular system, it's never too late to quit and recover some of that capacity. Within three months of quitting nicotine you can expect improvements in erection quality to follow.
Hormones
Chemical compounds called hormones regulate much of what goes on in our bodies. The stress hormone cortisol redirects blood flow to essential organs and muscles. Low testosterone can also negatively impact the ability to attain an erection.
Arousal level
It might seem obvious, but apparently it needs to be stated: the more turned you on, the easier it is to get an erection. On top of that, the more aroused you are, the better you can expect your erection quality to be and this the larger and harder your penis will get. The difference may be significant or negligible, and it becomes more evident with age. So you can absolutely expect to have a bigger boner when you're having relations with your partner than when you're masturbating by yourself. If that's not the case, you might want to re-examine that relationship.
Body weight
If you're underweight your body may struggle to produce enough testosterone in order to reach full erection strength. But with less body fat around the pubic area, more of the base of the penis will be exposed. And the skinnier the body it's attached to, the larger the penis will appear.
On the flip side, being overweight can also cause erectile dysfunction issues. Excess body fat will also build up around the base of the penis, hiding more of the shaft. And the fatter the body to which it is attached, the less impressive the penis will appear. While the fat pad is compressible (and is compressed for standardized penis measuring), it will only compress so much. Heaviness is also associated with other conditions that can hurt erectile function, such as high blood pressure and high cholesterol.
There's a happy medium of a healthy body weight where all the inputs that lead to good erections are closer to optimal. For most men that means there will be some pubic fat pad, generally in the 1/4-1/2" range. Having a pubic fat pad is also helpful to provide a little padding for sex, rather than bashing against your partner with your pubic bone only padded with a layer of skin.
Blood pressure
The purely vascular nature of the penis means it is very sensitive to changes in blood pressure. Erections are created by relaxing the arteries that carry blood into the penis and restricting the veins that cat blood out. The imbalance of increased inbound flow and decreased outbound flow drives up the internal blood pressure, filling and expanding the erectile tissues. Tada, it's a boner.
Somewhat counterintuitively, high blood pressure overall results in poorer erections. High blood pressure is often associated with hardening and narrowing of the blood vessel walls, which makes it more difficult for the penile veins to contact and the arteries to loosen, and thus leads to poor erection quality.
Low blood pressure can also have a negative impact on erections. Your fuck is a pressure vessel, and if your heart and arteries are struggling to provide inbound blood flow then your erections aren't going to be as impressive as they could be.
Body posture
Hope your body is positioned can affect the actual and apparent size of both your flaccid and erect penis.
It varies from man to man, but it's not at all unusual to experience differences in erection quality and size when sitting versus standing versus lying down. Your heart pumps blood differently in various positions, and gravity's pull leads to higher blood pressure in the parts of your body closer to the Earth. For many men, that means better erections and flaccid size when sitting or reclined.
The posture of your body also has an effect. Again, this varies from man to man, depending on the structure of your entire body, but in general you can expect that a slouching standing posture will result in decreased apparent size versus an upright posture. This comes down to the positioning of the pelvis; as the penis is mounted to the underside of the pelvis, so when your hips are tilted forward it will pull your dick back with them. There's a reason that "it's all in the hips" is a common phrase.
Certain body positions can also restrict blood flow into or out of the penis, impacting the size in that very moment. Again, this varies from man to man, but one example is squatting (as a position, not the exercise): the veins that drain blood away from the penis are clamped by the positioning of the thighs, leading to blood collecting in your dick and balls and both hanging lower.
Undergarments
To be clear and upfront: no properly sized underwear will hurt or limit the size of your erections or the shape of any curvature. It just doesn't work that way.
But, the undergarments that you do (or don't) wear can affect your flaccid size throughout the day. Underwear that is tighter on your dick compresses the amount of space that can be occupied by blood, so your soft penis will be smaller and scrotum sitting higher even after taking off the underwear simply due to that. Conversely, wearing looser underwear like boxers or pouch underwear (or going commando with none at all) won't compress your junk as much, allowing blood to flow more freely and everything to hand lower.
Again, this isn't permanent and has zero impact on your erection size. Guys that switch between looser and tighter undies can attest to the difference in their flaccid hang based on way they've worn that day.
Exercise
Fitness plays a huge role in erection quality. The better shape you're in, the better your cardiovascular health, and the better your body will be a pumping blood into your penis and keeping it there to sustain an erection. Improved fitness is also associated with lower body fat, and thus a reduced pubic fat pad and more exposed dick length. Being in good shape can also improve your flaccid size, as your body will be better at pumping blood overall and more will be flowing through your penis.
Conversely, while exercise can improve your penis size in general, in the time when you're actively engaged in exercise and immediately after it's not uncommon at all to experience shrinkage. And you exercise you're sending signals to your body to divert blood flow to your muscles. It's almost an instinctive physiological response to a perceived threat, as during our evolution into Homo sapiens lifting heavy things and sustained running was typically only associated with hunting or danger, situations in which a fully engorged penis is not helpful.
The good news is that while exercise may result in a retracting penis in the immediate minutes following until you're fully cooled and calmed down, long-term it leads to better erectile performance.
Marijuana
Weed is funny in how it affects men differently. For some men, marijuana ingestion can lead to more easily being aroused with harder and sustained erections. For others, it has the opposite effect: difficulty getting hard. Weed can also impact a man's ability to climax, with some men experiencing premature ejaculation when high while others can run into delayed orgasm or even find it impossible to finish. At least one study has shown that weed can help men with erectile dysfunction
And sometimes it depends on the strain of marijuana and the amount consumed. It's common enough to get hard for no reason when high that it has its own slang: "stoner boner".
Genetics
The single biggest contributor to the size of your penis is your DNA. It defines almost everything about your body, and multiple genes factor into your penis size in ways that aren't yet fully understood.
Both parents contribute genes that influence penis size, as does random mutation. Human DNA contains 3 billion base pairs (molecular sequences that encode building and operating instructions for our cells), half coming from the mother and half from the father. The process of pairing those genes to create the unique DNA of the child always results in some mistakes, 100-200 mutations every time.
Most of the time these genetic mutations and combinations aren't impactful; there are a lot of human genes that don't have any known purpose. Sometimes they can result in an unviable fetus or handicap in the infant, sometimes the result in surprising features in the child that neither parent possessed, like a blue-eyed child born to brown-eyed parents, or a boy with a large penis when there's no history of that on either side of the family.
While it can be safely assumed that penis size is largely hereditary, it's not always so. And sometimes it is but neither family line had the right combination of genes until now. Just based on their prevalence in the human population, it's safe to assume that the genetic combinations that lead to both micropenis and macropenis are recessive, so sometimes it takes the right parents for those genes to be expressed. And sometimes it is just random genetic mutation.
Either way, just became your dad has is a particular size doesn't mean you will be too.
Sleep
Rest is vitally important to the proper functioning of your entire body. Not being enough sleep messes with your ability to think straight, your energy levels, digestion, and even hormones. The more exhausted you are, the harder it will be to get hard.
Sleep is also when your body engages in most of its self-repairs functions and when a lot of growth during puberty happens (there's a reason teenagers sleep so much). The less sleep you're getting, the less your body can engage in those vital maintenance tasks and the poorer your overall performance will be.
Ligaments
The penis is attached at the top of its base to the pubic bone by the suspensory ligament. This ligament is what helps an erection stand up. It varies in tightness from guy to guy, some have trouble pulling their boners away from their stomachs while others practically hang freely even at full hardness. As with all things in the human body, over time the suspensory ligament will stretch out and erections won't point so far skywards as you age. For most men they can expect their erections to point somewhere in the range of 45° above or below perpendicular to the body.
A looser suspensory ligament will make a dick appear larger, but that's only a visual thing. The penis isn't actually any bigger, it just looks that way. A looser suspensory ligament can also require more hands-on guidance during sex, since swinging freely isn't conducive to hands-free insertion.
Cutting the suspensory ligament is a popular surgery amongst male porn stars, as it is effective in increasing the apparent visual size of the penis. But again, it has no bearing on the actual size and can be detrimental to practical sexual function.
Age
Penis size and age run on an arc. Obviously, from childhood up through puberty and to the start of adulthood you can expect your penis to grow. It doesn't happen in a linear fashion; dick growth often comes in fits and spurts just like height and body hair. And there's no defined age where penis growth stops thanks to several factors that influence the timing and rate of puberty, but typically penis growth stops in the late teens — but some end a few years earlier while others don't reach their peak size until their early 20s. But for most guys by the time they turn 18 they can expect to have reached their maximum size.
On the other side of the age curve, there are two sides to the penis size equation. Starting around age 40 to 50, men may experience a decrease in erection size. As the whole body ages it performs less well, including the cardiovascular system that powers erections. Conversely, decreasing elasticity in skin and muscles coupled with the unceasing pull of gravity will tug down on the testicles and flaccid penis, making your junk sag lower the older you get.
Erectile dysfunction
Obviously, men suffering from erectile dysfunction can have difficult felt an erection to begin with, but they can also struggle to reach their full size when they do manage to get hard. It's all the same physiological process from 0 to 100: loosening arteries and tightening veins.
Drugs like Viagra (Sildenafil) and Cialis (Tadalafil) are both vasodilators, and thus help to improve the flow of blood to the penis. This can make it easier for men dealing with physiological erectile dysfunction to achieve an erection, and can often impact their flaccid size with the overall improvement in circulation.
Men dealing with psychological erectile dysfunction are often helped by the treatment of a sex therapist who can help them with through the mental blocks that are impeding their ability to get properly aroused.
Diabetes
Type 2 diabetes often goes hand-in-hand with high blood pressure and obesity, both of which have serious negative impacts on erection quality. But the high blood sugar levels associated with diabetes are also damaging long-term to the blood vessels that supply the necessary blood to get an erection. It's also damaging to the nervous system, decreasing sensitivity and making it harder to for physical sensation to be stimulating enough to become aroused or reach climax.
Diet
Garbage in, garbage out, as they say. Your body is a biological machine, and it needs to be properly maintained (exercise) and fueled (food) to function properly. Good nutrition with minimal junk will allow you to perform closer to your peak, both in life and in bed.
That doesn’t mean you can’t treat yourself to red meat or beer or sweets or whatever. All things in moderation. It’s actually important for your mental health to be able to have the things that aren’t that good for you. They trigger the release of those feel-good endorphins. And when you feel good about yourself, you’ll also perform better sexually. Just keep it all in balance and you’ll be good.
Steroids
The same anabolic steroids that you can take to pump up your muscle mass and get all swole are not going to do anything for your penis. It won't get smaller, nor will it grow any bigger. Any erection quality benefits associated with steroids are actually those that come from exercising you must do to take full advantage of them — i.e. improving your cardiovascular health.
It is worth noting that steroids do have a well-documented impact on the size of your testicles, and it's not good. Chronic users of anabolic steroids will almost invariably end up suffering from hypogonadism: testicular atrophy averaging more than 20% by volume, with heavier users seeing greater volume loss. This is the body's reaction to the testosterone overdrive of anabolic steroids — the brain sends the testicles signals to dial back, and just like with muscles, the testosterone producing function of your testicles are a "use it or lose it" affair.
Random chance
We've all experienced that once-in-a-blue-moon megaboner that's so hard and big that you feel like it's going to pop. It's noticeably longer and thicker and you're looking at it and wondering "how do I get this to happen every time?"
I wish I had an answer for you. Many of the factors listed above are within your control, but a lot are not at all. Just like it takes the right combination of genes to end up with a huge dick, it takes the right combination of circumstances to get that random 110% erection. I guess when you've got it, don't let it go to waste!
More to read:
How big is *big*? Penis size chart for small, average, and large
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The pros and cons of having a big dick
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The correct way to measure your penis
Measuring your dick seems like it should be a simple thing. But somehow, it’s not. Here’s what you need to know to get the right numbers.
Do taller men have bigger penises? Here’s what the science says
It might make intuitive sense that a taller guy would have a bigger dick. After all, he has longer legs and bigger hands and all that other stuff. But the science isn’t so obvious.
