Sperm health
Sperm concentration
Sperm concentration is million sperm per millilitre. The lower reference limit cited by NICE is 16 million/ml.
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Short answer
Sperm concentration is the number of sperm in each millilitre of semen. The lower reference limit is 16 million per ml. A result at or above 16 million per ml is within the current reference range. A result below it is below the current reference value. Neither result diagnoses fertility.
Key takeaways
- The unit is million per ml, not the total in the pot.
- The previous WHO edition used 15 million per ml. NICE now cites 16.
- Home tests that only sort “above or below a threshold” are not a full concentration measurement.
- Oligozoospermia is the term for concentration below the reference limit.
| Measurement | Reference value | How to read it |
|---|---|---|
| Semen volume | 1.4 ml or more | Within the current reference range at or above this value |
| Sperm concentration | 16 million/ml or more | Within the current reference range at or above this value |
| Total sperm number | 39 million or more | Within the current reference range at or above this value |
| Total motility | 42 % or more | Within the current reference range at or above this value |
| Progressive motility | 30 % or more | Within the current reference range at or above this value |
| Vitality | 54 % or more | Within the current reference range at or above this value |
| Normal morphology | 4 % or more | Within the current reference range at or above this value |
NICE also cites semen pH of 7.2 or more. These are lower reference limits, not a fertility diagnosis.
Reading the line
Reports may say “sperm count”, “density” or “concentration”. If the unit is million/ml or ×10⁶/ml, it is concentration. If the unit is million per ejaculate, it is total sperm number. Mixing them up is the most common way to misread a report.
Why the limit moved
The WHO 5th edition (2010) used 15 million per ml. The 6th edition uses 16 million per ml, with a confidence interval of about 15 to 18. NICE NG257 quotes the 6th-edition figure. A laboratory still using an older comment on the form should say which manual it followed. The numbers are close. The principle is the same: this is a lower reference limit from a fertile reference group.
A low concentration
Clinicians describe concentration below the reference limit as oligozoospermia. Some services add mild, moderate and severe bands. Those bands are not part of the WHO reference table, so SemenBoost does not grade your result. Very low concentrations and azoospermia need a prompt repeat and specialist assessment, not a supplement trial as the first response.
The decoder will mark a concentration you enter as within or below the reference value. It will not call the result fertile or infertile.
Related
Sources
- WHO laboratory manual for the examination and processing of human semen, 6th edition — World Health Organization, 2021
- Fertility problems: assessment and treatment (NG257) — NICE, 2026
- NG257: investigation of fertility problems and management strategies — NICE, 2026
- Low sperm count — NHS
How this page was prepared
Drafted with automated research assistance and checked against the cited primary sources. A named clinician has not reviewed this page. Medical review is pending. Changes to reference values are not published automatically.