Normal Semen Volume
According to the most recent WHO reference values, a semen volume of 1.4 mL or greater (5th percentile lower reference limit) is considered normal, meaning volumes of 1-2 mL are entirely within the normal range for fertile men. 1
Evidence-Based Reference Values
The 2024 AUA/ASRM guidelines, citing WHO data from 3,589 men across 12 countries whose partners achieved pregnancy within 12 months, establish the lower reference limit at 1.4 mL (95% CI: 1.3-1.5 mL) 1. This represents the 5th percentile—meaning 95% of fertile men have volumes at or above this threshold 2.
What the Data Actually Show About Semen Volume
- Mean semen volume in fertile US men is 3.9 mL (median 3.7 mL), with a 5th-95th percentile range of 1.5-6.8 mL 3
- The probability of conception increases with sperm concentration up to 40×10⁶/mL, but semen volume itself has limited independent value in predicting pregnancy 4
- Volumes below 1.4-1.5 mL warrant clinical investigation only when accompanied by other abnormalities such as acidic pH (<7.0), azoospermia, or absent vas deferens, as these suggest ejaculatory duct obstruction or congenital bilateral absence of vas deferens 1
Clinical Context: When Low Volume Matters
Low semen volume (<1.4 mL) becomes clinically significant primarily in two scenarios 1:
- Obstructive pathology: When combined with acidic semen (pH <7.0), azoospermia, normal testosterone, and palpable vas deferens—this constellation suggests ejaculatory duct obstruction requiring transrectal ultrasound evaluation 1
- Retrograde ejaculation: Post-ejaculatory urinalysis should be performed when volume is <1 mL (except in bilateral vasal agenesis or hypogonadism) to diagnose retrograde ejaculation 1
Important Caveats
- Semen volume alone does not predict fertility—sperm concentration, morphology, and progressive motility are far more important parameters 4
- In men with high sperm counts (>200 million/mL) but low volume (<1 mL), sperm motility and viability are generally lower than in normal-volume specimens, though this represents a small subset of cases 5
- The 2002 guidelines cited a range of 1.5-5.0 mL as normal 1, but the more recent 2024 WHO-based data lowered the threshold to 1.4 mL based on larger, multinational fertile populations 1
Practical Takeaway
Volumes of 1-2 mL are medically normal and require no intervention unless accompanied by other semen abnormalities or clinical findings suggesting obstruction. 1 The perception that "normal" semen volume should be 3-5 mL reflects population averages rather than fertility thresholds—many fertile men have volumes well below 3 mL 2, 3.