Average Testicular Volume in Healthy Adult Males
The average testicular volume in healthy adult males is approximately 15-18 mL per testis when measured by ultrasound, with volumes below 12 mL considered atrophic and associated with impaired spermatogenesis. 1
Normal Reference Values
The established reference ranges for adult testicular volume vary slightly based on measurement method and population studied:
- Ultrasound measurements show median volumes of 18.9 mL (right testis) and 17.3 mL (left testis) when using the Lambert formula (0.71 coefficient), which is the most accurate calculation method 2
- Population-based studies in young adults (ages 19-27) demonstrate mean testicular volumes of 18.37 mL (left) and 18.13 mL (right) 3
- The right testis is consistently larger than the left testis across all measurement methods 2, 4
Clinical Significance of Volume Thresholds
Critical Volume Cutoffs:
- Below 12 mL: Definitively considered atrophic and associated with impaired spermatogenesis, increased risk of intratubular germ cell neoplasia (>34% risk in men under 30 with testicular cancer), and potential infertility 1
- 12-15 mL: Borderline-small range warranting clinical correlation with semen analysis and hormonal evaluation 1
- 15-18 mL: Generally considered the lower limit of normal, with adequate fertility potential 1
- Above 18 mL: Normal adult range associated with normal spermatogenesis 3
Measurement Methodology Considerations
The Lambert formula (Length × Width × Height × 0.71) is the recommended standard for calculating testicular volume from ultrasound measurements, as it provides the most accurate estimates compared to actual testicular volume 1, 5
Common Pitfalls to Avoid:
- Do not use the traditional ellipsoid formula (0.52 coefficient), as it systematically underestimates volume by 20-30% and may lead to inappropriate classification of testicular atrophy 1
- Clinical measurements with orchidometers or rulers overestimate ultrasound volumes by 70-80% in adults due to inclusion of scrotal skin and epididymis 6
- High-frequency probes (>10 MHz) should be used to maximize resolution and accurate caliper placement during ultrasound measurement 1
Correlation with Fertility Parameters
Testicular volume strongly correlates with reproductive function:
- Positive correlation with total sperm count, sperm concentration, and testosterone levels 4, 3
- Negative correlation with FSH and LH levels (elevated gonadotropins indicate testicular dysfunction) 3
- Volumes below 12 mL are associated with significantly reduced or absent sperm production, especially when FSH exceeds 7.6 IU/L 7
Age and Body Habitus Factors
- Volume is age-dependent only in males under 20 years, with relatively stable volumes in men aged 20 years and older 4
- Weak but significant positive correlations exist with height, body weight, and BMI 3
- History of cryptorchidism results in smaller average volumes (median 10.5 mL versus 14.1 mL in normal descent) 4