As with every other body part, testicle size varies from person to person, often with little or no effect on health.

Your testicle is an oval-shaped, sperm-producing organ within your scrotum. The average length of a testicle is between 4.5 to 5.1 centimeters (about 1.8 to 2 inches). Testicles that are less than 3.5 centimeters (about 1.4 inches) long are considered small.

Measuring the size of your testes is usually done with an ultrasound. This painless, noninvasive test uses sound waves to create images of the inside of your body on a computer screen.

Another, simpler tool used to measure testicle size is called an orchidometer. It’s basically a string of oval beads of different sizes, all approximately the size of a human testicle.

Your doctor can gently feel the size of your testicle and compare it to one of the beads on the orchidometer.

To measure at home, you can try to use a tape measure to get an approximate measurement. If you’re doing so, take a hot shower first to make sure your testicles aren’t withdrawn into your body for warmth. (This is also the time to do a testicle self-exam to check for lumps or other signs of testicular cancer.)

Your testicles have two main jobs:

  • producing sperm for reproduction
  • secreting the male hormone testosterone, which is important in the development of male physical characteristics and sex drive

Since sperm is produced in your testicles, you may produce less sperm than average if you have smaller balls. About 80 percent of a testicle’s volume is comprised of the seminiferous tubules, the tube-like structures that create sperm cells.

In a 2014 study published in the African Journal of Urology, researchers found that smaller testicle size corresponded to reduced sperm density.

However, you may have smaller-than-average testicles and be just as fertile as someone with larger testicles.

If you’re trying to father a child and you and your partner have been unsuccessful, you should consider seeing a fertility specialist. Your testosterone levels and sperm count can be measured to determine if they are related to your fertility troubles.

Having small testicles may be a good thing when it comes to your heart health.

Results from a study of 2,800 older Italian men seeking treatment for erectile dysfunction suggests that men with larger testicles may be at greater risk for cardiovascular disease than men with smaller testicles.

It’s not clear why this association exists, and researchers noted that because the study was of men with erectile dysfunction, the findings may not apply to all men.

Low levels of testosterone (low T) are associated with a higher risk of cardiovascular disease. However, treating low T with testosterone therapy may increase your chances of developing heart problems.

Studies have shown conflicting evidence on this subject. So, if you have low T, discuss testosterone therapy with your doctor and be sure to talk about the latest research on the risks and benefits of this treatment.

A group of Danish researchers looked at the connection between sperm quality, semen count, and testicle size. They found some evidence to suggest that poor sleep is associated with lower sperm counts. The connection between testicle size and poor sleep was inconclusive. More evidence is needed to better understand the connection between testicles, sperm quality, and sleep.

The researchers also noted that the men who reported frequent sleep disturbances tended to live unhealthier lives as well (for example, by smoking, eating a diet high in fat, and other unhealthy features). These lifestyle factors may play a greater role in sleep health than any other.

If you have small testicles, you may be more likely to be an involved, nurturing parent. Researchers have noted evolutionary developments in other primates to underscore these findings.

Male chimpanzees, for example, tend to have larger testicles and create a lot of sperm. Their focus seems more geared toward mating than protecting their young.

Male gorillas, on the other hand, tend to have smaller testicles and are quite protective of their offspring.

Researchers suggest that higher levels of testosterone, which is associated with larger testicles, may help steer some men toward behaviors other than the hands-on care of their children.

The researchers also cited previous studies that found that fathers who are much more involved with the day-to-day care of their children tend to have lower testosterone levels. The idea is that being a nurturing father may actually lower your testosterone levels. It’s unclear if low testosterone plays a part in making someone a more nurturing father or if being a nurturing father lowers testosterone.

Testicle size ranges from person to person, so it’s important to remember that size variations may have little or nothing to do with a diagnosable condition. When it comes to the health and function of your genitals, size differences may be meaningless.

There are, however, some conditions that cause testicles to be small.

Male hypogonadism

One in particular is called male hypogonadism.

Hypogonadism is a condition in which the body doesn’t produce enough testosterone to help ensure proper development of male characteristics, such as the penis, testicles, and muscle mass.

Primary hypogonadism

Hypogonadism may be caused by a testicular disorder, such as the testicles not responding to signals from the brain to make enough testosterone and sperm. This is called primary hypogonadism.

You may be born with this primary hypogonadism, or it can be caused by factors including:

  • infection
  • testicular torsion (a twisting of the spermatic cord within the testicle)
  • anabolic steroid abuse

Secondary hypogonadism

Secondary hypogonadism isn’t due to a problem that starts in the testicles. Instead, it’s a condition in which the pituitary gland in the brain doesn’t produce luteinizing hormone. Luteinizing hormone signals the testicles to make testosterone.

Varicocele

Another cause of small testicles is varicocele. Varicocele is an enlargement of the veins within the scrotum, typically due to problems with the valves that control blood flow in the veins. The bulging veins within the scrotum can cause the testicles to shrink and soften.

Undescended testes

Undescended testes can also cause small testicles. It’s a condition that develops prior to birth, when the testicles don’t move down into the scrotum. Undescended testes can usually be treated surgically during infancy.

It’s important to discuss your concerns about your testicle size with your doctor.

Your doctor can determine if your testicle size is a sign of an underlying health condition. It may be that your testicle size has nothing to do with erectile function or affects your sexual health in any way.

Talking with your doctor may give you some peace of mind and reassurance. It could also lead to treatment options if any are appropriate.

Treating infertility

If hypogonadism is affecting fertility, there are some medications that may help. Clomiphene (Clomid) is an oral medication that boosts hormones necessary for fertility.

It’s often used to help women who are having difficulty becoming pregnant, but it can be used to treat male infertility, too.

Injections of gonadotropins may also be effective if small balls have reduced your sperm density. Gonadotropins are hormones that stimulate activity in the testicles.

Testosterone replacement therapy (TRT) may provide benefits such as increased:

  • energy
  • sex drive
  • muscle mass

It may also contribute to a more positive mental outlook.

However, TRT should be supervised carefully by your doctor. There are some potentially serious side effects, such as prostate problems, abnormal aggressiveness, and circulation disorders.

Treating varicocele

Treating varicocele may or may not be necessary.

If the enlarged veins affect fertility or the health of your testicles, then surgery may be a good option. A surgeon can seal off the affected vein or veins, rerouting blood flow to the healthy veins in the scrotum.

The procedure may reverse atrophy of the testicle and may increase sperm production.

Treating undescended testes

If the condition is undescended testes, there is a surgical procedure that can be used to move the testes down into the scrotum. It’s called orchiopexy and is usually done before a boy’s first birthday.

Can male enhancements or supplements increase testicle size?

In general, there are no safe and effective procedures to boost testicular volume. Be cautious about any treatments sold in magazines, online, or on store shelves.

There are many “male enhancement” products that are advertised without any scientific evidence to back up their claims.

Taking supplements that are not approved by the U.S. Food and Drug Administration may be ineffective and expensive, and, at worst, dangerous to your health.

Smaller-than-average testicles may not affect your health in many cases.

If they are small due to an underlying condition, there are many treatment options.

The key to boosting your testosterone levels and sperm production, or treating another underlying condition, is talking with your doctor.