All penises get bigger when they’re erect — but there is some evidence of “showers” and “growers.”

“Showers” are people whose penises are the same length when they’re soft (flaccid) or hard (erect).

“Growers” are people whose penises get significantly longer and sometimes wider when they’re erect.

Let’s get into what the science says about the differences between the two, how to know which one you have, and more.

Yes! There’s been actual research on this.

Here’s how the researchers of a 2018 study published in IJIR, using data from 274 participants who have erectile dysfunction (ED), defined the difference between a “grower” and a “shower”:

  • Grower: penis grows much longer when going from being flaccid to being erect
  • Shower: penis doesn’t show any major change when going from flaccid to erect

Using penile duplex Doppler ultrasound (PDDU), the researchers measured penis length while in the flaccid state. They went on to inject a vasodilation substance into the spongy penis tissues before measuring the length while erect.

Researchers found an average change in size from flaccid to erect across all the participants, shower or grower, of about 4 centimeters (1.5 inches).

They used the 1.5-inch figure as a baseline for whether a participant was a shower or grower.

Does your penis grow more than 1.5 inches when you get erect? You’re a grower. Less than 1.5 inches? You’re a shower.

And out of the 274 reported participants, 73 (about 26 percent) of the participants were growers, and 205 were showers.

Growers experienced an average 2.1-inch change in length, and the showers had about a 1.2-inch change in length.

TErms to Know
  • Flaccid. This is the default state of the penis when you’re not sexually aroused. The penis is soft and hanging loosely from your groin area.
  • Stretched. This occurs when the penis isn’t erect or even sexually aroused, but is elongated from its normal state. This can happen to your penis whether you’re a shower or a grower.
  • Erect. This happens when the penis tissues fill up with blood when you get sexually aroused. The penis stays this way until you ejaculate or until you’re no longer aroused.

There are a few factors that contribute to whether you’re a shower or a grower:

  • Tissue elasticity. The capacity for your penile tissues to stretch and grow all contribute to how your penis looks. This includes the outer layers of skin, the inner layers of fibrous tissue (especially the tunica albuginea), and the ligaments that attach the penis to the body at the groin area. Your genes help determine how elastic your tissues are.
  • Collagen. Nearly half of the tissue in your penis is collagen, a protein that’s found throughout your body. Your genetics contribute to your body’s distribution of collagen, too.
  • Overall health. Blood flow is a key component to the erection process, so any condition that affects blood flow can contribute to how your penis grows when you get erect. ED, heart conditions, and diabetes can all affect your erection.

According to the 2018 IJIR study, just under two-thirds of the participants (about 74 percent) were showers.

But this isn’t necessarily reflective of the entire world population. There isn’t enough data to fully understand which one is more common.

In many cases, you’ll know without doing any tests to determine which group you fall into.

If your penis looks almost exactly the same whether it’s soft or hard, you’re probably a shower. If it looks drastically longer or bigger when it’s erect, you’re probably a grower.

But you can figure it out for sure by following some of the tips that the researchers provide in their study.

Here’s what to do:

  1. While flaccid, measure from the tip of the penis head (glans) to the base of the shaft. Make sure the bottom of the ruler, measuring tape, or whatever you’re using is flush with the skin around the base of the penis to get the most accurate measurement.
  2. Get erect. Do whatever you feel like doing to accomplish this — just don’t do it in public or around someone who did not consent to seeing it.
  3. Measure your penis again from tip to head. If the difference in length is more than 1.5 inches longer than your flaccid measurement, you’re a grower. If the difference is less than 1.5 inches, you’re a shower.

If you’re unable to get erect, you can use the stretched measurement:

  1. While you’re still flaccid, stretch out your penis by slowly pulling outward on the head or the skin around the head (this may be a little more comfortable).
  2. Stop stretching when it starts to feel uncomfortable.
  3. Measure your penis again from head to base.

Yep! Changes in tissue elasticity and collagen levels as you age have a lot to do with this.

You might become more of a shower as your tissues stretch out over time — the 2018 IJIR study found that growers were younger on average.

On the flip side, some people may become more of a grower as their tissues shrink or become less elastic over time. This causes the penis to retract and experience a larger increase in length when you get erect.

The study did find that growers experience a larger increase in length from their baseline penis size.

But this could simply be a result of the small sample size — fewer than 300 people out of approximately 3.8 billion people with penises in the world.

The participants in this study were receiving treatment for ED, so some underlying penile function issues may have also contributed to the overall increase in length.

What matters the most is how you feel about your penis.

If you’re comfortable with your penis and feel confident using it, then how it looks when it’s flaccid won’t make a difference in how satisfying your sex life is.

And both confidence and communication with your partner are crucial to a healthy sex life — these things are much more closely associated with having a solid, positive relationship that can then translate into a better, more communicative sexual relationship with that person.

The difference between growers and showers isn’t much of a difference at all.

According to limited research, the average change in length between the two is only an inch and a half. And what your penis looks like when it’s flaccid has no bearing on how it looks, feels, and works when it’s erect.

What matters is that you like your penis and you’re happy with it. Talk to a doctor or other healthcare provider if you’re concerned about your penis health.