Semen analysis results and the WHO 2021 reference limits

This page lists the reference limits in the World Health Organization's current laboratory manual, explains what each measure on a semen analysis report describes, and sets out how the test is prepared for and repeated. It explains a report; interpreting one for an individual is the work of the clinician who ordered it.

The WHO 2021 limits come from men whose partners conceived within a year

The sixth edition of the WHO laboratory manual for the examination and processing of human semen (2021) reports results from about 3,500 men in 12 countries whose partners conceived naturally within 12 months of trying, from data compiled by Campbell and colleagues (2021). The lower reference limit for each measure is the 5th centile: only 5 in 100 of these men had a lower result. The median, the middle result, is shown beside it.

• Semen volume: lower limit 1.4 mL; median 3.0 mL.
• Sperm concentration: lower limit 16 million per mL; median 66 million per mL.
• Total sperm number: lower limit 39 million per ejaculate; median 210 million.
• Progressive motility, the share of sperm moving forward: lower limit 30%; median 55%.
• Vitality, the share of sperm that are alive: lower limit 54%; median 78%.
• Normal forms, the share of sperm with a normal shape: lower limit 4%; median 14%.

A result below a lower limit is not a diagnosis of infertility

The WHO manual (2021) states plainly that these distributions cannot serve as a dividing line between fertile and subfertile men. Results overlap substantially between the two groups: some men with low results father a child within a year, and some men with normal results are in couples who do not conceive. The manual treats fertility as a continuum and notes that clinically useful decision limits have yet to be developed.

A normal result makes a male cause less likely without ruling one out. StatPearls (2026) estimates that in 10% to 20% of cases of male infertility the semen results are normal.

A report may use the 2010 limits or the 2021 limits

The previous edition of the manual, published in 2010, set the lower limit for sperm concentration at 15 million per mL and for total motility at 40% (StatPearls, 2026). Some US reference sources still quote the 2010 figures: MedlinePlus, from the US National Library of Medicine, lists a concentration of 15 million per mL, more than 39 million sperm in total, motility over 40% and normal forms over 4% (MedlinePlus, 2025). The differences between the two editions are small. The range printed beside each result on a report is the one that laboratory applied.

What each measure on a semen analysis report describes

• Volume is the amount of semen in the sample.
• Concentration is the number of sperm in each milliliter of semen, and total sperm number is the count in the whole sample. A low concentration is called oligozoospermia, or a low sperm count, and the complete absence of sperm is called azoospermia (StatPearls, 2026).
• Motility is the share of sperm that move. Low motility is called asthenozoospermia.
• Morphology is the share of sperm with a normal shape. A low share is called teratozoospermia. StatPearls (2026) notes that low motility or abnormal shape alongside a normal count is not considered a significant cause of infertility unless it is severe.
• Vitality is the share of sperm that are alive.
• pH, liquefaction time and white blood cells describe the fluid itself. MedlinePlus (2025) gives a pH of 7.2 to 8.0, liquefaction within 15 to 30 minutes and fewer than 1 million white blood cells per mL as the usual ranges. A higher white cell count can point to an infection.

Preparing for the test means 2 to 7 days without ejaculation

The WHO manual (2021) specifies a sample collected after at least 2 and at most 7 days without ejaculation, with the whole ejaculate collected, ideally in a private room near the laboratory so that analysis can begin within 30 minutes and no later than 60. MedlinePlus (2025) gives the same 2-to-7-day window, while StatPearls (2026) cites at least 3 days. The laboratory's own instructions are the ones that apply.

Some laboratories accept a sample collected at home. MedlinePlus (2025) describes collection kits that are returned to the laboratory within about an hour, kept at room or body temperature as instructed.

An abnormal result is repeated, on different timings in the US and UK

Semen results vary considerably from one sample to the next, so one abnormal result is not treated as final.

• US: StatPearls (2026) recommends at least two samples, at least one week apart and ideally one month apart. MedlinePlus (2025) notes that two or more samples may be requested within a week or two.
• UK: the NHS repeats an abnormal test, usually around 3 months after the first, and refers to a specialist if the second test also finds a problem (NHS, Low sperm count, 2024).

Home sperm tests measure less than a laboratory analysis

Home self-test kits count sperm, and some also estimate concentration or motility. MedlinePlus (2025) describes them as useful but notes that they give less information than a full semen analysis, which also measures volume, shape, pH and the other measures above.

The causes behind abnormal results, and when to seek an assessment, are covered in the guide to male fertility. The evidence on smoking, weight, alcohol and other habits is in the guide to sperm health.