Semen Analysis Normal Range: WHO 2021 Reference Values

The current WHO 2021 semen reference values are lower fifth centiles, not pass-or-fail fertility cutoffs. They show the point at or above which about 95% of men in the reference population scored for each parameter. Some men in couples who conceived had results below those values. Here are the current values with the correct units, their statistical limits, and the changes from WHO 2010.

WHO 2021 semen analysis reference values

The sixth edition of the WHO laboratory manual reports the following lower fifth-centile values. The confidence interval shows the uncertainty around the estimated fifth centile. It is not a personal result interval.

These values apply to a fertility semen analysis. A post-vasectomy semen analysis answers a different question: whether sperm remain after the procedure.

Why “normal range” is an imprecise term

The WHO values are one-sided lower reference points. They do not create a bounded interval with a normal low and high end. They are often called a semen analysis normal range. Lower reference values is the more accurate term.

The reference distributions came from approximately 3,500 men in 12 countries whose partners conceived naturally within 12 months. For each parameter, the fifth centile marks a value below which about 5% of that reference population scored. This has three practical limits:

1. A result at or above a lower reference value does not prove fertility. Pregnancy also depends on sperm functions that routine semen analysis does not measure and on the reproductive health of both partners.
2. A result below a lower reference value does not prove infertility. Men in the reference population conceived despite results below the fifth centile.
3. The parameters are not independent verdicts. The European Association of Urology guideline calls for a multiparameter assessment rather than using one value to classify an individual as fertile or infertile.

The 95% confidence interval in the table is also easy to misread. For sperm concentration, 16 million/mL is the estimated fifth centile, and 15 to 18 million/mL is the confidence interval around that population estimate. It does not mean an individual concentration from 15 to 18 million/mL is the WHO “normal range.”

What changed from WHO 2010 to WHO 2021

Reports and older guides often show 15 million/mL for concentration, 40% for total motility, and 32% for progressive motility. Those are WHO 2010 values. The current 2021 values changed several lower fifth centiles while leaving total sperm number and morphology unchanged.

The changes do not show that human fertility suddenly improved or worsened in 2021. They reflect an updated reference dataset and statistical distribution. A lab may also use a method-specific reference framework, so the framework named on the report belongs with the result.

Match each result to the right value and unit

Several report fields sound similar but cannot be substituted for one another:

• Semen volume is the fluid in the full sample, measured in milliliters.
• Sperm concentration is the number of sperm per milliliter, reported as million/mL or 10⁶/mL.
• Total sperm number is the number in the entire ejaculate, reported as millions per ejaculate. Volume multiplied by concentration gives the estimated total.
• Total motility includes progressive and non-progressive movement. Progressive motility includes sperm moving forward.
• Vitality is the percentage of live sperm. A live sperm may still be immotile.
• Morphology is the percentage of sperm meeting strict shape criteria. The 4% value refers to normal forms under the laboratory's morphology method.

WHO also uses consensus thresholds for some fields that are separate from the reference distributions above. Semen pH should be above 7.2, and peroxidase-positive leukocytes should be below 1 million/mL. “Round cells” are not automatically white blood cells. The AUA and ASRM guideline recommends further assessment when round cells exceed 1 million/mL to distinguish white blood cells from immature germ cells.

For a broader explanation of how count, motility, morphology, volume, and clinical context fit together, use our semen analysis results guide.

What happens when a result is below a lower reference value

One result is a snapshot. Abstinence time, incomplete collection, recent fever, transport conditions, and ordinary biological variation can change semen measurements. This is why a first result below one or more lower reference values often leads to repeat testing rather than an immediate conclusion.

The AUA and ASRM advise considering at least two semen analyses, ideally about one month apart, especially when the first has abnormal parameters. A repeat test should use a comparable comprehensive laboratory analysis and consistent preparation. If a home screen and a laboratory analysis conflict, the local laboratory analysis provides the fuller clinical dataset.

Persistent results below one or more lower reference values should be reviewed by a reproductive urologist or another clinician specializing in male fertility. The same applies when no sperm are found, sperm numbers are very low, or the report shows a concerning combination such as low volume with acidic pH and few or no sperm. A clinician can interpret the pattern alongside your history and decide whether a physical examination or further testing is indicated.

Results at or above every lower reference value do not end an evaluation when pregnancy has not occurred, there is recurrent pregnancy loss, or another reproductive concern remains. Semen reference values describe a population distribution. They do not predict the outcome for one person or couple.

If you need a first analysis or a standardized repeat, find a local lab with us. We arrange a physician-signed order for local lab-based testing and provide plain-English results interpretation, so you can act on the full report rather than one flagged number.