Doctors measure testicle size using a simple tool called an orchidometer — a set of oval beads in graduated sizes. The doctor compares each testicle to the beads to estimate volume in milliliters. This quick exam is standard during physicals and helps check for health issues like shrinkage, lumps, or hormonal problems.
How Do Doctors Measure Testicle Size During a Physical Exam?
The process is straightforward and takes less than a minute. You lie down or stand. The doctor feels your scrotum gently to locate each testicle. They then hold an orchidometer bead next to each testicle to find the closest size match.
Doctors also use their fingers to check for lumps, tenderness, or unusual firmness. The orchidometer gives a volume estimate in milliliters. Normal adult testicles range from 12 to 30 milliliters. Most men fall between 15 and 25 milliliters.
Some clinics now use ultrasound for more precise measurements. Ultrasound measures length, width, and depth to calculate volume. Research published in Journal of Urology found ultrasound is more accurate than orchidometer for detecting small changes. But orchidometer remains the standard for routine exams because it is fast and costs nothing extra.
What Is Normal Testicle Size and What Does Size Actually Mean?
Normal testicle size varies more than most people realize. One testicle is almost always slightly larger than the other. The left testicle hangs lower in most men. Neither difference means anything is wrong.
Size alone does not determine fertility or testosterone levels. Some men with smaller testicles produce plenty of sperm and normal testosterone. Some men with larger testicles have low counts. The relationship is not simple.
That said, very small testicles — under 10 milliliters — can signal a problem. Conditions like Klinefelter syndrome, undescended testicles from childhood, or testicular atrophy from steroid use can cause small size. The CDC reports about 1 in 500 males has Klinefelter syndrome, which often goes undiagnosed until adulthood.
Very large testicles are less common. They can indicate infection, fluid buildup, or rarely a tumor. Any sudden change in size deserves a doctor’s visit.
What Causes Testicles to Shrink or Grow?
Several factors can change testicle size over time. Some are temporary. Others are permanent.
| Cause | Effect on Size | Reversible? |
|---|---|---|
| Anabolic steroid use | Shrinkage (atrophy) | Often yes if stopped early |
| Varicocele (enlarged veins) | Shrinkage on affected side | Sometimes with surgery |
| Mumps after puberty | Inflammation then shrinkage | Partial recovery possible |
| Testicular torsion | Swelling then shrinkage if untreated | If treated within hours |
| Hydrocele (fluid sac) | Appears larger | Surgery drains fluid |
| Hormonal disorders | Gradual shrinkage | Hormone therapy may help |
| Aging | Slight decrease | Normal, not reversible |
Steroid use is the most common cause of testicular shrinkage in men who lift weights. Exogenous testosterone tells the brain to stop producing luteinizing hormone. Without that signal, the testicles stop making their own testosterone and shrink. Some men regain size after stopping, but recovery is not guaranteed.
Varicocele affects about 15 percent of men. It is a collection of enlarged veins in the scrotum. Over years it can cause the affected testicle to shrink. Surgery can sometimes reverse the shrinkage, especially in younger men.
How Do Doctors Measure Testicle Size for Fertility and Hormone Issues?
When a man has trouble conceiving or shows signs of low testosterone, measuring testicle size is one of the first steps. Small testicles often mean the sperm-producing tubes inside are not working well. The American Society for Reproductive Medicine notes that testicular volume under 15 milliliters is a red flag for fertility problems.
Doctors also check size when men report low libido, erectile dysfunction, or fatigue. If testicles are small and soft, it suggests the pituitary gland is not sending enough signals. If they are small and firm, it may point to a genetic condition like Klinefelter syndrome.
Blood tests follow to measure testosterone, LH, and FSH. The size measurement helps the doctor interpret those numbers. For example, a man with low testosterone and small testicles likely has a primary testicular problem. A man with low testosterone and normal-sized testicles may have a pituitary issue instead.
Ultrasound is often ordered in fertility workups. It provides exact measurements and can detect blockages in the sperm-carrying tubes. A study in Fertility and Sterility found that men with testicular volume under 12 milliliters had a 70 percent chance of low sperm count.
What to Avoid When Checking Your Own Testicle Size
Many men try to self-measure at home. This is not recommended. The orchidometer is a medical tool. Guessing by eye or using a ruler is unreliable. You will likely misjudge by several milliliters.
What you can do at home is a monthly self-exam. The American Urological Association recommends checking for lumps, hardness, or changes in size. Roll each testicle between your thumb and fingers. It should feel smooth and firm but not hard. A pea-sized lump is the most common sign of testicular cancer.
Do not panic over size differences. As noted, one testicle is normally slightly larger. The concern is change. If you notice one testicle has gotten smaller over months, or if it suddenly swells, see a doctor. Do not assume you can diagnose yourself.
A common myth is that larger testicles mean higher testosterone. This is not true. Testosterone is made by Leydig cells, which take up only a small portion of testicular volume. The bulk is sperm-producing tubules. Size tells you more about sperm production than hormone levels.
Common Misconceptions About Testicle Size
Misinformation about testicle size spreads fast online. Here are the most frequent myths and the facts.
- Myth: Testicle size determines masculinity. Fact: Size has nothing to do with masculinity, strength, or sexual performance.
- Myth: Cold weather permanently shrinks testicles. Fact: Cold causes temporary contraction. They return to normal size when warm.
- Myth: Masturbation shrinks testicles. Fact: No evidence supports this. Sexual activity does not change testicle size.
- Myth: Bigger testicles always mean more sperm. Fact: There is a rough correlation, but many men with average or below-average size have normal sperm counts.
- Myth: You can increase testicle size with supplements. Fact: As of 2026 there is no clinical evidence that any supplement increases testicle size. Companies that claim otherwise are selling false hope.
Testicle size is one data point among many. It matters most when tracked over time or combined with symptoms. A single measurement in isolation rarely tells the full story.
If you are concerned about your testicle size, the best step is a physical exam. Your doctor can measure accurately and explain what the number means for your specific health situation.
Frequently Asked Questions
How do doctors measure testicle size with an orchidometer?
The doctor holds each testicle and compares it to a series of oval beads in increasing sizes until they find the closest match. The bead size in milliliters becomes the estimated volume.
What is a normal testicle size in milliliters?
Normal adult testicles range from 12 to 30 milliliters, with most men falling between 15 and 25 milliliters. Size varies by age, genetics, and overall health.
Can testicle size affect fertility?
Yes, testicles under 15 milliliters are more likely to have lower sperm production. However, size alone does not guarantee infertility — a semen analysis gives the full picture.
Is it safe to measure testicle size at home?
Self-measurement is not accurate enough to be useful. Instead, do monthly self-exams to check for lumps or changes and see a doctor for any concerns.
