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What is a Micropenis: Causes, Symptoms, and Treatments

12 min read
What is a Micropenis: Causes, Symptoms, and Treatments

It's normal to worry that your penis might be smaller than average. The trouble is, it's not something many people feel they can talk about with friends or partners - so reliable information can be hard to find.

Here, we'll look at the subject of penis length in detail - specifically around 'micropenis', a medical condition where penis size is much smaller than normal.

We'll cover everything you need to know about the condition, including definitions, possible causes, treatment options, and some expert tips on dealing with a small penis.

What is a Micropenis: TL;DR 

  • A micropenis is defined as a penis that is 2.5 standard deviations below the average stretched length for a person's age and level of sexual development.
  • Micropenis is usually identified at birth when the penis is less than 0.75 inches when stretched.
  • Hormone and genetic factors, such as hormone disorders or genetic conditions like Down syndrome or androgen insensitivity syndrome, are common causes of micropenis.
  • Treatment options for micropenis vary based on age and may include testosterone therapy for children or surgical options for adults.
  • Penis extension devices have limited scientific evidence supporting their effectiveness in treating micropenis.

  • What is a Micropenis?

    We can start by looking at the technical definition of micropenis - then explain what that means in plain English.

    According to the largest study carried out on the condition, micropenis is "a medical diagnosis based on the correct measurement of length. For people with medically normal internal and external male genitalia, it's defined as a penis which is 2.5 standard deviations below the 'average stretched length' for their age and level of sexual development."

    Don't worry if that sounds complicated - there's a bit of math talk in there.

    Research estimates the average penis size as being 13.3cm (5.2 inches) when stretched. So, if we use the medical definition, this means an adult micropenis is one that's less than 9.3cm (3.6 inches) when stretched.

    Since the condition is usually first spotted when a person is born, the first indication that someone has micropenis would be a penis on a newborn that's less than 0.75 inches when stretched.

    How to know if you have a micropenis

    Ultimately, whether or not you have a micropenis depends on your penis size.

    According to the Harriet Lane Handbook (the Johns Hopkins published manual for pediatric specialists) - the following table should be used as age-related size guidance:

    Age Length
    6 to 12 months Less than 2.3 centimeters (0.9 inches)
    1 to 2 years Less than 2.6 centimeters (1.02 inches)
    2 to 3 years Less than 2.9 centimeters (1.14 inches)
    3 to 4 years Less than 3.3 centimeters (1.3 inches)
    4 to 5 years Less than 3.5 centimeters (1.38 inches)
     5 to 6 years Less than 3.8 centimeters (1.5 inches)
    6 to 7 years Less than 3.9 centimeters (1.54 inches)
    7 to 8 years Less than 3.7 centimeters (1.46 inches)
    8 to 9 years Less than 3.8 centimeters (1.5 inches)
    9 to 10 years Less than 3.8 centimeters (1.5 inches)
    10 to 11 years Less than 3.7 centimeters (1.46 inches)
    Adult Less than 9.3 centimeters (3.66 inches)

    If you're now reaching for a measuring tape, hold on for a second. You'll notice that the medical definition of micropenis requires "correct measurement of length" - and this isn't quite as straightforward as it might first seem.

    With this in mind, it's worth understanding how to measure your penis accurately - and which part you should be measuring.

    How to measure your penis correctly

    Measuring your penis accurately relies on something known as "stretched penile length" (SPL).

    Using an SPL measurement is considered to be more accurate than erect penis length because penises often bend a little when erect, plus they are more difficult to measure accurately as the base of the penis can be harder to access.

    Manchester University (part of the UK's National Health Service) offers some practical advice on measuring stretched penile length. They recommend the following technique:

    1. In a standing position, place your flat left hand firmly against the part of your torso above your penis. This will help to move or compress any body fat that is hiding the true base of your penis.

    2. Using your right hand, pull back your foreskin (if you have one), then hold the head of your penis between your thumb and forefinger.

    3. Extend your right hand, bringing the head of your penis forward. You'll need to use firm pressure - but not enough to cause any pain.

      Since this is a medical procedure, it can be a little uncomfortable to get an accurate SPL - so erect penis length works as a fairly accurate backup.

      If you're measuring your penis erect, make sure you do so with a soft measuring tape to account for any curve

      Also, remember to compress your torso to find the true base of your penis - even a little belly fat can seem to reduce your size significantly.

      Where to measure

      There are lots of different ideas about where to start measuring penis length from. The answer is fairly simple.Measure along the top of your penis - from the base to the end of your glans (the tip).

      In medical terms, this is known as the 'dorsal' side.

      Again though, it's important to press any body fat you might have inward as much as possible - so you can access the true base of your penis.

      What are the most common causes of micropenis?

      Typically, micropenis develops before a baby is born. Often, it will be the only abnormality that's detected by blood tests during pregnancy.

      Specialists have identified two key factors that they think may lead to the micropenis condition being present - hormones and genetics.

      Let's take a look at both in a little more detail:

      Diagram on the Common Causes of Micropenis


      During a baby's development in the womb, different hormones cause different types of growth. This process is generally controlled by the pituitary gland.

      Early in the development of the fetus, a growth hormone called "placental human chorionic gonadotropin" stimulates the developing testes to produce testosterone. Testosterone is proven to be a factor in deciding penis size in early development.

      If a hormone disorder leads to testosterone being blocked at this early stage, a baby's penis growth could be affected.

      After around 14 weeks of development, a baby is exposed to another hormone - referred to as "luteinizing hormone". This hormone ordinarily stimulates testosterone development in specific cells within the testicles. However, if the production of this luteinizing hormone or testosterone is blocked, studies suggest this could also prevent penile growth.


      Research into genetic factors that could contribute to micropenis is slim. In fact, research done in this field sometimes refers to genital abnormalities as "hidden" factors in the condition.

      Despite this, some links between genetics and micropenis are thought to exist. Studies into chromosomal disorders suggest that the following conditions could play a part in the development of micropenis symptoms:

       Down syndrome A chromosomal disorder that affects how the body forms and functions
      Androgen insensitivity syndrome A condition that makes the body resistant to androgens - hormones that play a part in male development.
      Klinefelter syndrome A chromosomal disorder where additional female chromosomes develop in males, leading to some growth and mood abnormalities

      Exposure to drugs and pesticides

      While it's believed the majority of micropenis cases are due to hormone or genetic factors, a recent school of thought considers the impact of external factors that could contribute to micropenis development.

      Studies suggest that environmental pollutants - such as chlorinated pesticides - may cause micropenis and other genital abnormalities in a male baby.

      Also, studies into the use of some estrogen-based fertility drugs are thought to have an impact on children - and even grandchildren - of people who have used them, with some cases showing the development of micropenis.

      Can micropenis be treated?

      Treatment options for an abnormally small penis vary based on age. In children, where the genitals are still developing, testosterone treatment can often significantly support penis growth. In adults, urologists may decide to explore surgical options instead.

      In some rare cases, specialists may explore gender reassignment options - if the person in question doesn't feel that the normal sexual identities associated with having a penis are appropriate for them.

      Diagram on the Treatment Options for Micropenis

      Testosterone therapy

      If diagnosed before the age of eight, a pediatric urologist will often decide that hormone therapy is the right course of action for micropenis.

      This will usually involve a course of three testosterone treatments. A 2013 study shows this approach will usually result in the penis growing to or beyond the expected length after the treatment.

      A slightly different hormone therapy may still be effective in children over the age of eight.

      The same study showed that treatment using a follicle-stimulating hormone can even be effective in children older than 11 years.

      Penis enlargement surgery

      When the potential for natural penile growth has stopped, surgery is considered to be one of the best medical options for enhancing penis length.

      The type of surgery a urologist decides on will depend on you and the size of your penis. One option could be detaching the ligament that holds the penis up when erect. This can give the perception of more length.

      Another option, flap surgery, involves grafting additional tissue from another part of the body. While effective, this approach is riskier - as it may limit the natural function of the penis, making sexual intercourse more difficult.

      Gender reassignment

      Although we'll mention gender reassignment so we give a full overview, it's a technique that's very rarely used today. Gender reassignment was previously only used in children who had micropenis.

      Today though, gender reassignment therapy would only generally be used in collaboration with male-to-female lifelong hormone therapy, supported by a specialist psychologist.

      Penis extension devices

      Although there are very few medical studies that look atf the use of penis extension devices in people with a less-than-average-sized penis, the studies that have been carried out look very promising.

      The research carried out documented size increases of around 1.7cm and also suggested the possibility of girth increases - including in the glans.

      As the least intrusive of the treatment options, a penis extension device is often favored as a person's first treatment method.

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      How is micropenis diagnosed?

      Micropenis is diagnosed following a medical examination. A doctor will accurately measure your penis and then compare it to the normal penis size for someone your age.

      While most doctors will be able to accurately measure your penis, it's often a good idea to make sure it's a doctor will knowledge of urological conditions who carries out the diagnosis. This is because micropenis is a rare condition - so misdiagnosis is reasonably common.

      Mistaken micropenis diagnosis

      Micropenis is actually just one of a number of 'inconspicuous penis' diagnoses. Since it's the rarest of a number of similar conditions, misdiagnosis can occur.

      Before deciding on a micropenis diagnosis, a urology specialist will usually rule out some other, more common conditions that could mistakenly present as a micropenis.

      Webbed Penis

      Webbed penis occurs when additional skin connects the shaft of the penis and the scrotum. Usually, this skin begins on the underside of the penis towards the base.

      However, if you have a webbed penis, the scrotum skin starts much higher up the shaft and pulls the penis inwards.

      Usually, a fairly simple surgical procedure will release this skin, making the penis appear much larger.

      Buried Penis

      A buried penis occurs when some or all of your penis is concealed by body fat and/or skin.

      Since the latest obesity figures from the CDC (Centers for Disease Control and Prevention) suggest that 41.9% of people in the US can be considered obese, it's reasonable to assume that many people suffer from buried penis to some degree.

      Diet and lifestyle changes can make a huge difference to the amount of body fat you carry - and some doctors will even consider liposuction if a buried penis is causing you distress or impacting your ability to enjoy normal sex life.

      Psychological implications: How to live with a micropenis

      As much as we're continually told that "size doesn't matter", there's a nagging feeling for most guys that it actually does.

      So, how can you live happily with a micropenis?

      1. Try to separate fact from fiction

      Do a quick Google search around 'micropenis' or 'small penis' and it won't take long before you find articles that claim people with smaller penises may have trouble fathering children due to a claimed link between small penises and a low sperm count.

      These stories are generally based on a pioneering 2018 study carried out to look at the links between penis length and fertility.

      Despite many mainstream media outlets claiming a link was found between micropenis and low fertility, this simply is not true.

      In fact, a later 2020 study went on to show that there was no link between reduced penis size and testosterone levels.

      It's useful to take this information onboard. While the media seems to like to associate masculinity with penis size, science is quite clear that there really is no link.

      2. Understand that penetration is only one part of sex

      The idea of sex being entirely about penetration is one that generally only exists in the mind of men.

      The truth is, the typical flaccid penis is only just over 3.61 inches (9.16cm) long - which isn't much longer than a penis that is considered a micropenis. What's more, 84% of women say that penis length just doesn't matter to them.

      So, why doesn't penis size matter to most women? Generally, it's about how much value they put on penetration.

      In fact, a large and long-term 2016 study into what makes women orgasm explains that "sexual desire, sexual self-esteem, and openness of sexual communication with partners" and "mutual sexual initiations and partner’s good sexual techniques" we far more important than penetration alone.

      Penetration is often seen as the 'goal' of sex. In truth, foreplay, oral sex, and attitudes towards sex are far more important, no matter how large or small your penis may be.

      3. Make sex more varied

      Now we've got a better idea of what partners want from sex; it's a good idea to think about how you can vary sex to account for these factors.

      If you want to make sure you and your partner are enjoying sex as much as possible (and you're enjoying the self-esteem boost that comes with this), then try mixing up your sex play by:

      • Focusing on foreplay: Building sexual desire is all in the head. Experiment with different foreplay techniques - talk about sex, make your partner feel desired, learn what turns them on, and don't rush!

      • Play with toys: Until we evolve to have multi-speed vibrating penises, sex toys will almost always be more effective at making our partners orgasm than we are! Add toys to your sexual encounters - and don't be afraid to experiment with toys for both of you, including cock rings, sleeves, and penis pumps.

      • Be spontaneous: Sex in a relationship can sometimes feel like it's being done out of expectation rather than desire. A partner feeling desired can be a huge turn-on - so passion and spontaneity will almost always beat having a couple of extra inches.

        4. Understand that worries about a small penis are often just in your head

        It's easy to think that your thought process is real - just a voice given to real-world problems. Generally, though, this isn't the case.

        Just because you think there's a problem, it doesn't mean there actually is one.

        Ever worried about being too fat, too thin, not muscular enough, or not tall enough? When people meet you, it's extremely unlikely that they're thinking any of this. Instead, they're probably instead worrying about what you think of them.

        The same is true of thoughts about your penis.

        In fact, worries about our own bodies are so common that there's an actual name for the condition when it affects your daily life - body dysmorphia. If you suffer from this type of condition, there's rarely any physical change that will make you happy with your body.

        Whether or not you have a psychological condition, talking to a counselor can be a very positive move if you worry a lot about having a small penis. A good therapist can help you work out why you have these feelings and give you some strategies that will help you deal with negative feelings going forward.

        Micropenis: A summary

        In adults, a micropenis is one that's less than 9.3cm (3.6 inches) when stretched or erect. Correct measurement of your penis is essential before a doctor will diagnose you as having the condition.

        The micropenis condition is generally considered to be a result of hormone imbalances when a baby develops - although there's some evidence to suggest it can sometimes be hormone related.

        There are treatment options available. For children, these tend to be hormone therapies - but for adults, surgery or the use of a penis extension device is generally favored.

        Speaking to a doctor before deciding you have micropenis is important as there are other very similar 'inconspicuous penis' conditions that are more treatable.

        Ultimately, having a smaller-than-average penis doesn't have the impact on sex or masturbation that many people think it would. Partners tend to put a lot less importance on size than they do other factors.

        As such, understanding how penis size is really viewed can help you deal with worries that you have about penis size - as can varying your sexual practices and speaking to a therapist about strategies to feel more positive about your body.

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