What Is Sperm Vitality? What It Measures and Why It Matters
Written by: Mate Health Clinical Education Team
Medically reviewed by: Nicholas Farber, MD
Published: Sep 2026
Sperm vitality is the percentage of living sperm in a semen sample, measured by whether each sperm has an intact cell membrane. It matters most when motility is low, because a sperm can be alive without moving. Under the WHO 6th Edition (2021), the lower fifth-percentile reference value for vitality is 54 percent live sperm.
Most people reading a semen analysis focus on two numbers: how many sperm there are, and how many are moving. Vitality answers a different question. It measures how many sperm are alive. When motility is low, vitality can change how the result is interpreted.
Table of Contents
Sperm Vitality vs. Sperm Motility
Motility measures how many sperm are moving. Vitality measures how many are alive. A moving sperm is alive, but a still sperm can be either alive or dead, and vitality can tell the two apart.
Every sperm cell is surrounded by a membrane. In a living cell, that membrane is intact and functioning. When a sperm dies, the membrane loses its integrity. Vitality testing identifies which sperm still have an intact membrane, a key marker of a living cell.
This is why the two measurements are related but not the same. Motility and vitality usually track together, so when motility is normal, vitality often adds limited additional information. When motility is low, the two can diverge, and that is where a vitality result becomes particularly useful.
How Sperm Vitality Is Measured
Sperm vitality is measured in a laboratory by assessing the membrane integrity of sperm cells. The result is reported as the percentage of sperm that are alive.
The WHO 6th Edition (2021) describes established laboratory methods for assessing vitality. Although the specific technique can vary by laboratory, the underlying principle is the same: living sperm have intact, functioning cell membranes, while dead sperm do not.
What a Sperm Vitality Result Means
Under the WHO 6th Edition (2021), the lower fifth-percentile reference value for vitality is 54 percent live sperm. A result below that reference value is not, by itself, a diagnosis.
Vitality is reported as the percentage of sperm that are alive. As with every parameter in a semen analysis, the WHO reference value is a statistical benchmark, not a pass-or-fail line, and results can vary from sample to sample. Here is where vitality sits alongside several other common semen analysis parameters.
| Parameter | WHO 6th Edition (2021) Fifth-Percentile Reference Value | What It Measures |
|---|---|---|
| Vitality | 54% live sperm | Proportion of living sperm, by membrane integrity |
| Total motility | 42% | Proportion of sperm that are moving |
| Progressive motility | 30% | Proportion moving forward effectively |
| Concentration | 16 million per mL | Sperm per milliliter of semen |
Why Vitality Matters When Motility Is Low
When motility is low, vitality tells you whether the still sperm are alive or dead. Those are two different situations that a motility number alone cannot separate, and they can lead a physician down different paths.
The WHO 6th Edition (2021) recommends assessing vitality when total motility is below 40 percent. The reason is practical. When most sperm are moving, they are clearly alive, and a separate vitality test adds little. When motility is low, a larger share of sperm are not moving, and the question becomes why.
There are two different possibilities:
- The still sperm are alive but not moving. This points toward a motility problem, where the cells are living but something is limiting their movement.
- The still sperm are dead. This points toward a vitality problem, a different situation that may lead to a different path of evaluation.
Both can produce a low motility number, so they may look similar until vitality is measured. That is why vitality is most informative when motility is reduced.
Necrozoospermia and Asthenozoospermia
Asthenozoospermia means reduced sperm motility. Necrozoospermia means reduced sperm vitality, or a high proportion of dead sperm. Vitality testing helps distinguish between the two.
These terms remain common in clinical literature and may be used by physicians when describing semen analysis findings. The WHO 6th Edition emphasizes interpreting semen parameters together rather than treating any single reference value as a diagnostic label.
Vitality on a Mate Health Semen Analysis
Vitality is included in Mate Health's Advanced Semen Analysis, which reports 22 parameters, including vitality and DNA fragmentation. Vitality is also available as an optional add-on to the Comprehensive Semen Analysis.
Testing is performed by Mate Health's CLIA-certified, CAP-accredited high-complexity andrology laboratory using WHO 6th Edition (2021) methodology. For most men with normal motility, vitality often provides limited additional information beyond motility. When motility is low, vitality is one of the parameters that can help a physician better understand what the result means.
Frequently Asked Questions
Can Sperm Be Alive but Not Moving?
Yes. A sperm can have an intact, living cell membrane and still not move. This is exactly the situation vitality testing is designed to identify, and it is why vitality and motility are separate measurements.
Is Low Sperm Vitality the Same as a Low Sperm Count?
No. Sperm count measures how many sperm are present. Vitality measures what proportion of them are alive. A sample can have a normal count with low vitality, or a low count with normal vitality.
What Is the Lower Reference Value for Sperm Vitality?
Under the WHO 6th Edition (2021), the lower fifth-percentile reference value for vitality is 54 percent live sperm. It is a statistical reference point, not a pass-or-fail threshold or a diagnostic cutoff by itself.
When Is Sperm Vitality Tested?
Vitality is most useful when total motility is below 40 percent. When motility is normal, moving sperm are already known to be alive, so a separate vitality test often adds limited additional information.
How Is Sperm Vitality Tested at Home?
Vitality is a laboratory measurement, not something assessed at home. With a mail-in service, a sample is collected at home and analyzed at a certified laboratory, where vitality is measured using WHO 6th Edition (2021) methodology.
Key Takeaways
- Sperm vitality is the percentage of living sperm, measured by membrane integrity, not by movement.
- A sperm can be alive and still not move, which is why vitality and motility are related but distinct.
- The WHO 6th Edition (2021) lower fifth-percentile reference value for vitality is 54 percent, and vitality is assessed when total motility is below 40 percent.
- When motility is low, vitality separates living-but-still sperm from dead sperm, two different clinical situations.
- At Mate Health, vitality is included in the Advanced Semen Analysis and is also available as an optional add-on to the Comprehensive Semen Analysis.
This article is for educational purposes and does not replace evaluation by a physician.
References
- World Health Organization. WHO Laboratory Manual for the Examination and Processing of Human Semen. 6th ed. Geneva: WHO; 2021.
- Agarwal A, Sharma RK, Gupta S, et al. Sperm vitality and necrozoospermia. World Journal of Men's Health. 2022;40(2):228-242.
- Boitrelle F, Shah R, Saleh R, et al. The Sixth Edition of the WHO Manual for Human Semen Analysis: A Critical Review and SWOT Analysis. Life. 2021;11(12):1368.