Average Testicular Volume in Adult Males
The average testicular volume in healthy adult males is approximately 18 mL when measured by ultrasound using the Lambert formula (Length × Width × Height × 0.71). 1, 2
Normal Reference Values
Adult males (18+ years): Mean testicular volume is 18.37 mL (left) and 18.13 mL (right) based on a large population study of 1,139 young men aged 19-27 years 2
Adolescent development: Testicular volume reaches >3 mL by age 13 years, with intensive growth starting around age 10 years 3, 4
Late adolescence (16.5-18 years): Testicular volume ranges from 6-22 mL, approaching adult values 4
Pediatric reference: For boys aged 0-18 years, Z-score regression equations derived from age provide age-specific normal ranges, with testicular volume positively correlated with age using logarithmic transformation 5
Measurement Technique Considerations
The Lambert formula (0.71 coefficient) is the recommended calculation method for testicular volume from ultrasound measurements, as it provides the most accurate estimates compared to actual testicular volume 1
The traditional ellipsoid formula (Length × Width × Height × 0.52) systematically underestimates volume by 20-30% and should not be used for clinical decision-making 1
High-frequency ultrasound probes (>10 MHz) should be used to maximize resolution and accurate caliper placement 1
Measurements should include three perpendicular dimensions (length, width, height) obtained on axial slices 1
Factors Affecting Testicular Volume
Body habitus correlates weakly but significantly with testicular size:
Testicular volume shows positive correlation with height (r = 0.470), weight (r = 0.504), and body surface area (r = 0.549) 2, 6
BMI has a weak positive correlation with testicular volume 2
Age-related changes:
Testicular volume remains relatively stable in adult life until the 8th decade, when reduction occurs 6
Advancing age is an independent risk factor for reduced testicular size in elderly men 6
Pathological conditions associated with reduced volume:
Malnutrition (reduced standardized body weight) independently reduces testicular volume 6
Alcoholism, malignancy, and chronic terminal illness are independent risk factors for decreased testicular size 6
History of cryptorchidism significantly reduces testicular volume 1
Clinical Significance of Volume Thresholds
Testicular volumes <12 mL are definitively considered atrophic and associated with significant pathology including impaired spermatogenesis and increased risk of intratubular germ cell neoplasia 1
Volumes 12-15 mL are considered borderline-small and warrant clinical correlation 1
Mean testicular volume strongly correlates with total sperm count and sperm concentration 1
In men under 30 years with volume <12 mL, there is a >34% risk of intratubular germ cell neoplasia in the contralateral testis if testicular cancer is present 1
Geographic and Population Variations
No significant geographic variation exists in normal adult testicular volume, though studies show slight differences in mean values across populations that likely reflect measurement technique variations rather than true biological differences 7
- The weighted mean testicular volume across geographic regions (North America, Europe, Asia) for adult males is consistently 10-11 cm³ in various study populations, though this represents different patient populations (often PCOS studies measuring ovarian parameters) 7
Common Measurement Pitfalls
Technical errors in caliper placement during ultrasound can lead to incorrect measurements and falsely low volume calculations 1
External caliper measurements overestimate testicular dimensions by 5.7 mm (length), 2.9 mm (thickness), and 1.4 mm (width) compared to ultrasound 3
Repeat measurements by the same sonographer using standardized technique minimize inter-scan variability 1
Size discrepancy between testes >2 mL or 20% warrants further evaluation to exclude pathology 1