Testicular Size Perception and When to Seek Evaluation
Your testicles are likely normal in size, and comparing them to online images—especially during erection—is misleading because penile erection does not change testicular size, and internet images are often distorted by camera angles, body proportions, and selection bias. 1
Understanding Normal Testicular Volume
- Testicular volumes of 12 mL or greater are considered normal, with the typical range for healthy adult men being 13–18 mL per testis. 1
- The Prader orchidometer (a chain of oval beads) provides a good clinical estimate of testicular volume and is easier and more cost-effective than ultrasound for routine assessment. 1
- Testicular length of approximately 4 cm corresponds to a volume of 15–18 mL, which falls well within the normal range. 1
- Healthy Vietnamese men averaged 13.64 ± 3.44 mL per testis, demonstrating significant normal variation across populations. 2
Why Erection State Is Irrelevant
- Testicular size does not change with penile erection—the testes remain the same volume whether you are flaccid or erect. 1
- The scrotum may appear tighter or more contracted during sexual arousal due to cremasteric muscle contraction, which can create the visual illusion of smaller testicles, but actual testicular volume is unchanged. 1, 3
- Online images are unreliable references because camera angles, body proportions (a larger penis or smaller body frame makes testicles appear smaller), and selective posting of unusual cases distort perception. 1
When Testicular Size Warrants Medical Evaluation
High-Priority Scenarios Requiring Urology Referral:
Testicular volume consistently measured at <12 mL by a clinician using an orchidometer or ultrasound, especially if accompanied by: 1
- History of undescended testicles (cryptorchidism) in childhood, which substantially increases cancer risk and mandates closer surveillance. 1
- Age under 30–40 years, as men in this age group with testicular volume <12 mL have a ≥34% risk of intratubular germ cell neoplasia if testicular cancer develops. 1
- Infertility concerns or difficulty conceiving after 12 months of unprotected intercourse, as testicular volume strongly correlates with total sperm count and sperm concentration. 1, 4
Size discrepancy between the two testicles >2 mL or 20%, which warrants scrotal ultrasound to exclude pathology such as varicocele, testicular mass, or atrophy. 1
Palpable testicular mass, firmness, or nodule, regardless of testicular size, as this may indicate malignancy. 1
Rapid testicular atrophy (shrinking over weeks to months), which suggests acute pathology requiring urgent evaluation. 1
What to Do If You Remain Concerned
Step 1: Obtain Objective Measurement
- Schedule a physical examination with a urologist or primary care physician who can measure testicular volume using a Prader orchidometer or order scrotal ultrasound if physical examination is difficult. 1, 3
- Self-assessment is unreliable—only clinical measurement can determine whether your testicles are truly small. 1
Step 2: Assess Fertility Status (If Relevant)
- If you have concerns about fertility or plan to have children, request a semen analysis to evaluate sperm concentration, motility, and morphology, as testicular volume alone cannot definitively predict fertility. 1, 4
- Hormonal evaluation (FSH, LH, testosterone) should be performed if semen analysis shows abnormalities, especially sperm concentration <10 million/mL. 5, 1
Step 3: Rule Out Reversible Causes
- History of undescended testicles, mumps orchitis, testicular trauma, or torsion can cause testicular atrophy and should be disclosed to your physician. 6
- Chronic medication use (opioids, corticosteroids, anabolic steroids) or systemic diseases (diabetes, liver cirrhosis, hemochromatosis) can suppress testicular function and should be evaluated. 3, 6
Common Pitfalls to Avoid
- Do not use exogenous testosterone or anabolic steroids if you have any current or future fertility concerns, as these completely suppress spermatogenesis through negative feedback and can cause azoospermia that takes months to years to recover. 1, 3
- Do not rely on internet images or self-comparison as a diagnostic tool—camera angles, body proportions, and selection bias make these comparisons meaningless. 1
- Do not assume small testicles mean infertility—men with testicular volumes of 10–12 mL typically have oligospermia (reduced sperm count) rather than azoospermia (complete absence of sperm), and many remain fertile. 3, 7
Bottom Line
If you have no history of undescended testicles, no difficulty conceiving, no palpable masses, and no rapid change in testicular size, your testicles are almost certainly normal. 1 The perception of small size during erection is a visual illusion caused by scrotal contraction and unreliable internet comparisons. 1 If you remain concerned, obtain objective measurement by a clinician using an orchidometer or ultrasound—self-assessment is unreliable. 1, 3