What is the normal width of a testicle (testis) that is 4cm in length?

Normal Testicular Width for a 4cm Length Testicle

For a testicle measuring 4cm in length, the expected width should be approximately 2.5-3.0 cm, corresponding to a testicular volume of 12-15 mL, which falls within the normal adult range. 1

Understanding Normal Testicular Proportions

Using established anatomical proportions, a 4cm testicular length corresponds to:

• Width: 2.5-3.0 cm 1
• Height (depth): 2.0-2.5 cm 1, 2
• Estimated volume: 12-15 mL 1

This places the testicle at or above the critical 12 mL threshold that defines normal testicular size. 1

Clinical Significance of the 12 mL Threshold

Testicular volumes below 12 mL are considered atrophic and warrant investigation, particularly in men under 40 years of age. 3, 1, 4

Key clinical implications:

• Volumes <12 mL in men under 40 carry a 34% risk of intratubular germ cell neoplasia in the contralateral testis 1, 4, 2
• Testicular atrophy requires evaluation for underlying causes including cryptorchidism history, prior trauma, infections, or genetic conditions 4
• The strongest correlations with testicular function occur with volumes ≥14 mL, with impaired sperm quantity and quality below this threshold 5

Critical Distinction: Tumor Size vs. Testicular Size

Do not confuse the 4cm threshold mentioned in cancer guidelines with normal testicular dimensions—they refer to entirely different measurements. 1, 4

• The 4cm cutoff in testicular cancer guidelines refers to tumor dimensions within the testis, not overall testicular size 1, 4
• In seminoma, tumors ≥4cm with rete testis invasion carry a 32% relapse risk, but this applies only to pathologic tumor measurements 1, 4
• This distinction is critical to avoid unnecessary anxiety when measuring normal testicular dimensions 1

Measurement Considerations

If precise volume determination is needed for clinical decision-making, ultrasound is superior to external measurements. 1, 6, 7

• External measurements with calipers overestimate testicular dimensions by 5.7mm in length, 2.9mm in thickness, and 1.4mm in width compared to ultrasound 6
• Clinical methods overestimate ultrasound volumes by 70-80% in adults and 150-250% in prepubertal subjects due to inclusion of scrotal skin and epididymis 7, 8
• Ultrasound provides the gold standard for accurate, reproducible testicular volume assessment 7, 8

When to Seek Evaluation

Urgent ultrasound evaluation is warranted for: 1, 4

• Pain, firmness, or palpable mass within the testis 1
• History of undescended testis, trauma, or infections 1
• Any concern for testicular pathology in the setting of risk factors 4