Understand the test
Semen analysis
What a semen analysis measures, the WHO reference limits NICE uses, and why one result is not a fertility diagnosis.
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Short answer
A semen analysis is a laboratory examination of a semen sample. It reports volume, sperm number, how sperm move, and usually how they are shaped. NICE says these results should be compared with World Health Organization reference values. A result inside or outside those values does not, on its own, tell you that you are fertile or infertile.
Key takeaways
- The test describes the sample. It does not certify fertility.
- NICE NG257 uses WHO lower reference limits, including 16 million sperm per ml and 42% total motility.
- Those limits are valid for a WHO laboratory semen analysis, not for every home kit.
- An abnormal first result is usually repeated. Azoospermia or severe oligozoospermia is repeated sooner.
| 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.
What the laboratory is looking at
Semen is the whole fluid. Sperm are the cells inside it. A standard analysis separates those ideas. Volume is how much fluid was produced. Concentration is how many sperm are in each millilitre. Total sperm number is how many sperm are in the whole ejaculate. Motility is movement. Morphology is shape. Some laboratories also report vitality, the percentage of sperm that are alive, and pH.
NICE NG257, published on 31 March 2026, tells clinicians to compare an initial semen analysis with the WHO reference values. NICE also notes that those ranges are only valid for the semen analysis tests set out by WHO. A home test that measures one threshold, or a phone video that estimates motility, is not the same examination.
How to read a reference limit
The figures in the table on this page are lower reference limits. They come from the 5th centile of men in couples who conceived within a year. They are not a pass mark you must clear to cause a pregnancy, and they are not a target of 100%.
A concentration of 16 million per ml is the lower reference value, not a score of “normal fertility”. Men with results above every limit sometimes need fertility care. Men with a result below a limit sometimes conceive without treatment. The NHS makes the same point in plain language: a low sperm count can make conception harder, and it can still be possible.
Why a single sample is not the whole story
Sperm production takes roughly two to three months. NICE says that if the first semen analysis is abnormal, a repeat confirmatory test should be offered, ideally three months later so a cycle of sperm formation can finish. If the finding is azoospermia or severe oligozoospermia, the repeat should happen as soon as possible.
Illness, a fever, a short or very long gap since the last ejaculation, a spilled sample, or a delay getting the sample to the laboratory can change the report. That is why preparation and the laboratory’s own instructions matter.
Where people have the test
In the UK, the NHS route usually starts with a GP when a couple has been trying to conceive. Private laboratories also offer the test. In the United States, testing is arranged through a clinician, urologist, fertility clinic or laboratory, and insurance coverage varies. SemenBoost does not publish a price until a provider’s price has been verified.
When to seek medical advice
Seek an assessment if you and a partner have been trying to conceive without success for the period your own clinician uses, if a semen analysis is abnormal, if you have very few or no sperm, testicular pain or a swelling, a history of undescended testes, cancer treatment, pelvic or testicular surgery, or if you are using testosterone or anabolic steroids. Sudden severe testicular pain needs urgent care, not a repeat semen form.
Do not use a supplement, a home kit, or this website in place of that assessment.
Questions
Does a normal semen analysis mean I am fertile?
No. A result inside the reference limits is reassuring about those measurements. It does not prove that conception will happen, and it does not look at every possible cause of infertility.
Does a low result mean I am infertile?
No. Below a reference value means that measurement sits outside the current reference range. Clinicians usually confirm an abnormal result and interpret it with the rest of your history. The NHS says conception may still be possible.
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.