Sperm count: what's normal and what the number means

In everyday speech, "sperm count" gets used for almost any sperm number, but on a lab report it has a specific meaning: total sperm count, also called total sperm number. It is the concentration of sperm (millions per millilitre) multiplied by the volume of the sample. A man with 20 million sperm per mL and 3 mL of semen has a total count of 60 million.

That makes it different from sperm concentration, which only tells you how densely packed the sperm are. Concentration can look higher or lower depending on how much fluid the prostate and seminal vesicles add, so total count gives a fuller picture of how many sperm actually reached the ejaculate.

The World Health Organization (WHO) lower reference limit is 39 million sperm per ejaculate.^1,2 That figure is the 5th centile of men whose partners got pregnant within a year: 95% of those recently fertile men had a higher count.² A total count below the limit is usually described as oligozoospermia; no sperm at all is azoospermia.

What is a normal sperm count?

A total sperm count of 39 million or more per ejaculate sits at or above the WHO lower reference limit. Falling below it flags a result for follow-up, not a verdict on your fertility.

The current reference values come from pooled data on more than 3,500 men from twelve countries whose partners had recently conceived.¹ The lower limits mark the bottom 5% of that group. The researchers behind the 2021 figures are clear that these values do not draw a hard line between fertile and subfertile men.¹

In practice, that means plenty of men below 39 million still father children, and some men above it struggle. Sperm count is one piece of a semen analysis, read alongside motility, morphology and your partner's own fertility.

Why does sperm count change between tests?

Sperm count varies a lot within the same man from one sample to the next. That is why a single low result is normally repeated before anyone draws conclusions.

In one study of men who each gave five or more samples, sperm count was the most variable measure in the whole analysis: the typical within-man variation was around 54% in fertility patients and 46% in healthy donors.⁴ The author concluded that at least three samples were needed for a reliable picture.⁴

Part of the swing is timing and circumstance: how long since you last ejaculated, whether the whole sample made it into the pot, and what was going on in the weeks before. Sperm take weeks to develop (see spermatogenesis), so today's sample reflects your health a couple of months ago as much as your health today. Our post on how semen changes day to day covers the volume side of this.

Are sperm counts falling?

A large 2017 meta-regression found that sperm counts among Western men not selected for fertility fell by more than half between 1973 and 2011. The finding is influential but still debated.

The analysis pooled 185 studies covering 42,935 men.³ Among men from North America, Europe, Australia and New Zealand who were not selected by fertility status, mean total sperm count fell by an estimated 59.3% over the period, about 1.6% a year.³ No significant trend was seen in the studies from South America, Asia and Africa.³

The authors themselves note that reported declines have been controversial, and pooling decades of studies with different lab methods is hard to do cleanly.³ It is a population trend, not a prediction about any individual man.

What should I do if my sperm count is low?

Repeat the test first, ideally at the same lab and following its instructions closely. If it is still low, ask your GP for a referral to a urologist or fertility specialist.

A persistently low count is worth investigating because it has many possible causes, some treatable, including hormonal problems, a varicocele and certain medicines such as testosterone therapy. A specialist will usually check hormones such as FSH and testosterone and examine the testes.

Talk to a doctor sooner if you and your partner have been trying to conceive without success, if you have a history of undescended testes, testicular surgery or cancer treatment, or if you notice a lump, swelling or pain in the scrotum. Our guide to lifestyle factors that affect male fertility covers the day-to-day side.

Common questions

Is sperm count the same as sperm concentration?

No. Concentration is sperm per millilitre; total sperm count is concentration multiplied by semen volume. A lab report lists both, and they can tell slightly different stories if your semen volume is unusually high or low.

Can you tell your sperm count by looking at semen?

Not reliably. Semen that looks thick, thin or watery can still contain a normal number of sperm, because most of the fluid comes from the glands rather than the testes. Only a laboratory count under a microscope gives a real figure.

How many semen tests do I need?

At least two is standard if the first result is abnormal, because sperm count varies so much from sample to sample. One study suggested three samples were needed for a reliable estimate.⁴

Sources

Campbell MJ, Lotti F, Baldi E, et al. Distribution of semen examination results 2020 - A follow up of data collated for the WHO semen analysis manual 2010. Andrology. 2021;9(3):817-822. PubMed
Cooper TG, Noonan E, von Eckardstein S, et al. World Health Organization reference values for human semen characteristics. Hum Reprod Update. 2010;16(3):231-245. PubMed
Levine H, Jørgensen N, Martino-Andrade A, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Hum Reprod Update. 2017;23(6):646-659. PubMed
Keel BA. Within- and between-subject variation in semen parameters in infertile men and normal semen donors. Fertil Steril. 2006;85(1):128-134. PubMed

Not medical advice. Written by Eric Stephens from the research cited above; not reviewed by a doctor. If something worries you, see a GP.