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Short answer: Semen volume is the amount of fluid you ejaculate. Fertility depends much more on the sperm inside it: how many there are, how well they swim and how they are shaped. Supplements sold for semen volume are not fertility treatment, and the best trials of fertility supplements show small or no benefit. If you have been trying for a baby for a year, get a semen analysis and see a doctor.
Key facts at a glance
| Question | What the evidence says |
|---|---|
| Is volume the same as fertility? | No. A semen analysis measures volume, sperm count, motility and morphology separately (MedlinePlus) |
| How common is male-factor infertility? | About one-third of infertility cases stem from male reproductive issues (NICHD) |
| Do antioxidants help? | A 2022 Cochrane review of 90 trials found they may increase pregnancy and live birth, but the evidence is low to very low certainty (Cochrane) |
| Do zinc and folic acid help? | A large trial of 2,370 men found no improvement in live birth or most sperm measures (Schisterman et al., JAMA 2020) |
| When to get tested | After a year of trying, or sooner if your partner is 36 or over or you know of a possible problem (NHS) |
Volume, count, motility, morphology: what is the difference?
A semen analysis looks at several separate things (MedlinePlus):
- Volume: how much semen is in the sample.
- Sperm concentration: how many sperm are in each millilitre.
- Total sperm count: the number of sperm in the whole sample.
- Motility: the percentage of sperm that are moving well.
- Morphology: the percentage of sperm with a normal shape.
The WHO 6th edition lower reference limits, as reproduced by an NHS andrology laboratory, are (MFT, citing WHO 2021):
| Measure | Lower reference limit |
|---|---|
| Semen volume | 1.4 mL |
| Sperm concentration | 16 million per mL |
| Total sperm number | 39 million per ejaculate |
| Progressive motility | 30% |
| Normal forms (morphology) | 4% |
| Vitality (live sperm) | 54% |
These are 5th percentile values from men whose partners conceived within a year. Falling below one of them does not mean you are infertile, and being above all of them does not guarantee fertility. They are a starting point for a doctor’s assessment.
Why more volume does not mean more fertility
A man can have plenty of semen with few or no sperm in it, and a man with lower volume can have a normal sperm count. Some conditions that cause low volume, such as blocked ejaculatory ducts, also cause very low sperm numbers, so low volume is worth checking (Roberts and Jarvi, 2009). But increasing the fluid alone does not add sperm or make them swim better. For more on what drives volume, see our guide on how to increase semen volume.
What causes male infertility?
According to the US National Institute of Child Health and Human Development (NICHD) (NICHD):
- The most common problems affect how the testicles work.
- A varicocele (an enlarged vein in the testicle) is the most common cause of reduced sperm production and is present in about 40% of men with infertility problems.
- Hormone imbalances and blockages also play a part.
- In about 50% of cases, no cause can be found.
The NHS adds testicular damage from infection, surgery or injury, ejaculation disorders, hypogonadism (low testosterone), and some medicines and drugs, including anabolic steroids, chemotherapy, sulfasalazine, cannabis and cocaine (NHS: causes of infertility). Smoking, excess alcohol and exposure to some pesticides, solvents and metals are listed as risk factors (NHS: infertility).
Retrograde ejaculation, where semen goes into the bladder, reduces or stops semen coming out. The NHS says it is not dangerous but can affect the ability to father a child, and that options such as extracting sperm for assisted conception exist (NHS: ejaculation problems).
What does research say about supplements for male fertility?
Antioxidants
The largest summary is the Cochrane review on antioxidants for male subfertility, last updated in 2022. It included 90 randomised trials with 10,303 subfertile men and 20 different antioxidants (Cochrane summary). Its findings:
- Live birth: antioxidants may increase live birth, with an estimated 17 to 27 per 100 couples having a baby compared with 16 per 100 without. But this benefit disappeared when only the better-quality studies were analysed.
- Clinical pregnancy: may increase, from 15 per 100 to between 20 and 30 per 100, with low certainty.
- Miscarriage: no evidence of a difference.
- Side effects: mild stomach upset was somewhat more common with antioxidants.
- Overall: the authors rated the evidence low to very low certainty and called it inconclusive, mainly because trials were small and poorly reported.
In short, antioxidants are not proven to help, but they are not ruled out either. These trials involved men already seen at fertility clinics, not healthy men using a volume supplement.
Zinc and folic acid
The Folic Acid and Zinc Supplementation Trial (FAZST) is one of the biggest trials in this area. It randomly gave 2,370 men either 5 mg of folic acid plus 30 mg of zinc daily, or a placebo, for 6 months while their partners had fertility treatment (Schisterman et al., JAMA 2020; NICHD). Results:
- Live birth rates were about the same in both groups (34% vs 35%).
- Sperm concentration, motility, morphology and total motile count did not improve.
- Men taking the supplement had more sperm DNA fragmentation and more stomach and bowel symptoms.
The authors concluded these supplements cannot be recommended to treat male infertility. This matters because zinc is a common ingredient in male supplements.
What about herbal “volume” formulas?
We did not find high-quality trials showing that over-the-counter semen volume supplements improve sperm count, motility, pregnancy or live birth. Until such evidence exists, treat any fertility claims for them with caution.
Where do volume supplements fit?
Volume supplements are not fertility treatment. They are marketed for the amount of semen, which is a different thing from the quality of the sperm. If you are trying to conceive, a supplement should not delay a semen analysis or a visit to a fertility doctor. Supplements can also have side effects, as FAZST showed for zinc and folic acid.
If you want to read about one of these products for its intended purpose, our Semenax review covers it. Our how we review page explains our methods.
When should you get a semen analysis and see a fertility doctor?
The NHS suggests seeing a GP if you have not conceived after a year of trying. More than 8 in 10 couples where the woman is under 40 conceive naturally within a year of regular unprotected sex. See a doctor sooner if your partner is 36 or older, or if either of you knows of a possible fertility problem (NHS: infertility).
For men, see a doctor sooner if you have:
- had testicular surgery, injury, undescended testicles or cancer treatment
- little or no semen at orgasm, or cloudy urine after sex
- erection or ejaculation problems that keep happening
- used anabolic steroids
For a semen analysis, MedlinePlus says you should avoid ejaculating for 2 to 7 days before giving the sample (MedlinePlus). One abnormal result is not a diagnosis. Doctors often repeat the test.
Erection problems deserve attention in their own right. The NHS says they may be a sign of a treatable condition such as high blood pressure, high cholesterol or diabetes (NHS).
FAQ
Does more semen mean I am more fertile?
No. Fertility depends mainly on sperm count, movement and shape. A large volume can contain few sperm.
Can supplements increase sperm count?
The strongest evidence is weak. A Cochrane review found antioxidants may help pregnancy rates, but only with low-certainty evidence. A large trial of zinc and folic acid found no improvement in sperm measures or live birth.
Is zinc good for male fertility?
In the FAZST trial, 30 mg of zinc plus 5 mg of folic acid daily for 6 months did not improve sperm quality or live birth, and caused more stomach symptoms and more sperm DNA damage than placebo.
Are semen volume pills a fertility treatment?
No. They are marketed for the amount of fluid, not sperm quality. If you are trying for a baby, get a semen analysis and see a doctor.
How long should I try before getting tested?
The NHS suggests seeing a GP after a year of trying, or sooner if your partner is 36 or over or you know of a possible problem.
What happens at a semen analysis?
You give a sample after 2 to 7 days without ejaculating. The lab measures volume, sperm count and concentration, motility, morphology and other features.
Can low semen volume affect fertility?
It can, if it is caused by something like retrograde ejaculation or a blockage. That is a reason to get it checked, not a reason to take a volume supplement.
Sources
- MedlinePlus. Semen analysis. https://medlineplus.gov/lab-tests/semen-analysis/
- Manchester University NHS Foundation Trust, Andrology Laboratories. Lower reference limits for semen characteristics (WHO 6th edition, 2021). https://mft.nhs.uk/app/uploads/sites/4/2023/01/Lower-reference-limits-2021.pdf
- World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th edition. 2021. https://www.who.int/publications/i/item/9789240030787
- NICHD. What causes male infertility? https://www.nichd.nih.gov/health/topics/menshealth/conditioninfo/infertility
- Cochrane. Antioxidants for male subfertility (review summary, 2022 update). https://www.cochrane.org/evidence/CD007411_antioxidants-male-subfertility
- Schisterman EF, et al. Effect of folic acid and zinc supplementation in men on semen quality and live birth among couples undergoing infertility treatment: a randomized clinical trial. JAMA. 2020. https://europepmc.org/article/MED/31910279
- NICHD. Folic Acid and Zinc Supplementation Trial (FAZST). https://www.nichd.nih.gov/about/org/dir/dph/officebranch/eb/folic-acid-zinc
- Roberts M, Jarvi K. Steps in the investigation and management of low semen volume in the infertile man. Canadian Urological Association Journal. 2009. https://pmc.ncbi.nlm.nih.gov/articles/PMC2792416/
- NHS. Infertility. https://www.nhs.uk/conditions/infertility/
- NHS. Infertility: causes. https://www.nhs.uk/conditions/infertility/causes/
- NHS. Ejaculation problems. https://www.nhs.uk/conditions/ejaculation-problems/
- NHS. Erectile dysfunction (impotence). https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/