What Causes Small Testicles?

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The size of a man's testicles is largely determined by his genes. Testicles usually start out small and grow larger as the boy enters puberty. However, they can remain small if the boy has a hormone deficiency or if he has a condition that affects the testicles.

Your body needs certain hormones to develop normally. If your body can't make enough of these hormones, your testicles will be small. A hormone deficiency can be caused by a problem with the pituitary gland or with the testicles themselves. It can also be caused by certain medicines or by using street drugs.

Let's look at some key points about testicle sizes, including how to measure, what's considered "normal," and if there is a reason to be concerned.

What Are the Testicles Responsible For?

The testicles are responsible for making sperm and testosterone. Testosterone is a hormone that helps with the development of the male sex organs and with the growth of body hair. It also helps to increase muscle mass and strength.

The testicles are also responsible for the sex drive in men. Testosterone levels usually peak in a man's early 20s. After that, levels of the hormone start to decrease slowly. This decrease can lead to a decrease in sex drive, as well as a decrease in energy levels and muscle mass.

What is the Average Testicle Size?

The average length of a testicle is between 4.5 and 5.1 centimeters, which is about 1.8 to 2 inches. A testicle that is less than 3.5 centimeters, or about 1.4 inches, is considered small. This means that the average testicle is between 1.4 and 2 inches long, and the testicles when measured together should be around 4 to 5 centimeters (1.6 to 2 inches) in length.

Keep in mind that depending on your height, weight, and body type, your testicles may be a different size than what is considered "average." For example, taller men tend to have larger testicles than shorter men.

How to Measure Testicle Size

There are a couple different ways that you can measure your testicle size. The most common way is to use a ruler or measuring tape. Place the ruler or measuring tape against your body where the top of your testicle meets your body. Then, use your other hand to gently pull your testicle down so that it is hanging away from your body. Once your testicle is hanging, take note of the length of the ruler or measuring tape. This is the length of your testicle.

For the width, place the ruler or measuring tape around the thickest part of your testicle. Once again, take note of the measurement. This is the width of your testicle.

If you don’t have a ruler or measuring tape, you can also use a string or piece of yarn. Place the string or yarn against your body where the top of your testicle meets your body. Then, use your other hand to gently pull your testicle down so that it is hanging away from your body. Once your testicle is hanging, take note of the length of the string or yarn, and then compare it to a ruler or measuring tape scale online or in a book.

How Can You Measure Your Testes?

The sac that contains the testicles (scrotum) can be measured by a doctor using either an ultrasound, or orchidometer. These measurements can help determine if someone has microorchidism, which is when the testicles are smaller than normal.

Both of these methods are painless and noninvasive.

What is Microorchidism?

Microorchidism is defined as a condition where the testicles are smaller than normal. This can be caused by a variety of factors, including genetic abnormalities, hormonal imbalances, or infections. 

The condition can lead to infertility, and treatment may be necessary to preserve fertility. If left untreated, microorchidism can also lead to testicular cancer, due to the increased risk of DNA damage in the smaller testicles.

Can Testicle Size Affect Testosterone and Fertility?

Because the job of the testicles is to make sperm and testosterone, it stands to reason that testicle size would affect fertility. Small testicles might produce less sperm and testosterone, which could lead to fertility problems. However, there is no direct link between testicle size and fertility. Small testicles are not necessarily a sign of low sperm production or low testosterone levels. In fact, most men with small testicles are fertile.

The main factor that affects fertility is the number of sperm produced. Sperm count can be affected by many factors, including health, lifestyle, and genetics. Testicle size does mean there is less sperm in each ejaculation, but men with small testicles can still have a normal sperm count, and therefore, normal fertility.

If you're concerned about your testicle size, or think it might be affecting your fertility, talk to your doctor. They can recommend you to a fertility specialist, who can help you figure out if there are any underlying fertility issues.

What Causes Small Testicles

There can be several reasons for why someone might have small testicles. Let's take a look at a few potential causes and explore them further.

Male Hypogonadism

When it comes to the size of one's testicles, testosterone levels play a role. Testosterone is a hormone produced in the testicles and is responsible for the development of male sexual characteristics. When testosterone levels are low, it can lead to smaller testicles.

Male hypogonadism is a condition where the body does not produce enough testosterone. This can be due to a number of different factors, such as an injury to the testicles, a genetic disorder, or a problem with the pituitary gland. Treatment for male hypogonadism typically involves testosterone replacement therapy.

Klinefelter Syndrome

Klinefelter syndrome is a genetic disorder that affects males. It is caused by the presence of an extra chromosome in the cells. This extra chromosome is a sex chromosome, which means that it is responsible for the development of male sexual characteristics. Klinefelter syndrome can lead to smaller testicles, as well as other symptoms such as infertility and breast development. Treatment can be done through hormone replacement therapy and other medical interventions.

Primary Hypogonadism or Secondary Hypogonadism

Primary and secondary hypogonadism are separate from male hypogonadism but can also lead to small testicles.

Primary hypogonadism is a condition where the testicles are not able to produce testosterone due to a problem with the testicles themselves. This can be caused by an infection, injury, or tumor.

Secondary hypogonadism is a condition where the testicles are able to produce testosterone but the pituitary gland is not able to signal the testicles to produce testosterone. This can be caused by a problem with the pituitary gland or damage to the hypothalamus.

Both of these conditions can be treated with testosterone replacement therapy and other treatments depending on the underlying cause.


A varicocele is a condition where the veins in the testicles are dilated and can cause pain, swelling, and fertility problems. Varicoceles are the most common cause of low sperm count and can be treated with surgery.

This condition is not directly linked to small testicles, but can lead to small testicles if left untreated. Symptoms of a varicocele include:

  • Pain or discomfort in the testicles
  • A feeling of heaviness in the testicles
  • A dull ache in the lower abdomen or groin
  • Visibly enlarged veins in the scrotum

If you have any of these symptoms, you should see a doctor for a diagnosis.

Tetes That Have Yet To Drop

Small testicles can also be seen in boys who have yet to experience puberty. In this case, the testicles will usually grow larger as puberty progresses. Some men may never experience full testicular growth, however, and will have small testicles throughout their lives. 

In youth, small testicles can also be caused by undescended testicles, a condition where the testicles have not descended into the scrotum. This is usually treated with surgery to move the testicles into the scrotum.

When Should I See a Doctor About My Testicle Size?

If you are concerned about the size of your testicles, you should talk to your doctor. He or she can perform a physical examination to determine if your testicles are the right size for your age and body type. Your doctor can also order tests to check for a hormone deficiency or other underlying condition.

In some cases, small testicles may be a sign of a serious health condition, such as testicular cancer. Therefore, it's important to see a doctor if you are concerned about the size of your testicles.

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This blog post is for educational purposes only and does not constitute medical or other professional advice. Your specific circumstances should be discussed with a healthcare provider. All statements of opinion represent the writers' judgement at the time of publication and are subject to change. Phoenix and its affiliates provide no express or implied endorsements of third parties or their advice, opinions, information, products, or services.

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