Ejaculation runs in two phases: first your body gathers semen behind a closed valve, then muscles pump it out. On average 2 to 6 millilitres are released, roughly a teaspoon. It normally holds tens of millions of sperm cells per millilitre.
Most of that fluid does not come from your testicles. Around 70 percent comes from your seminal vesicles and about 20 percent from your prostate.
That surprises almost everyone. The sperm cells themselves are, by volume, a rounding error.
How does ejaculation work exactly?
Ejaculation has two steps that follow closely on each other. In the emission phase, sperm move from your epididymis to your urethra, where fluid from your prostate and seminal vesicles joins them. In the expulsion phase, pelvic floor muscles squeeze rhythmically and shoot the lot out.
Between those two phases sits a valve. The bladder neck closes, so your semen goes out and not into your bladder.
If that valve does not close well, the semen goes the wrong way. That is called retrograde ejaculation, and then your orgasm is normal but little or nothing comes out. Some prostate medications can cause it.
The point where you can no longer hold it back is called the point of inevitability. It sits roughly two to four seconds before the first muscle contraction.
What is a normal amount?
Roughly 2 to 6 millilitres per ejaculation, averaging around 3 millilitres. Less after a short break, more after a few days. That swing is normal and says nothing on its own about your fertility.
What more often goes wrong is the perception: men compare themselves to porn. That is not a reference value, that is a production.
The World Health Organization set reference values in 2010 based on men who fathered a child within a year (Cooper, 2010). That is the key nuance to those numbers: they are not normal values, they are lower bounds of a fertile group.
| What is measured | WHO lower limit (2010) | What it describes |
|---|---|---|
| Volume | 1.5 ml | How much fluid is released |
| Concentration | 15 million per ml | How many sperm per millilitre |
| Total count | 39 million per ejaculate | Volume times concentration |
| Motility | 40% moving | Whether they can swim |
| Shape | 4% normal form | Whether they are well built |
That 4 percent for shape reads like a typo. It is not. In healthy, fertile men the vast majority of sperm cells are not perfectly formed.
I find it the most useful number in the whole table. It shows how much margin your body built in.
How often is normal?
There is no normal number. Research on frequency measures averages, not prescriptions, and the spread between men is enormous. From several times a day to a few times a month, all of it falls within what people normally do.
For semen quality it does matter somewhat. A break of 2 to 7 days is used for a semen analysis, because too short and too long both shift the picture.
That is a laboratory agreement, not a rule for living. It says nothing about how often you should have sex.
What else comes out?
Before ejaculation, pre-cum is released from the Cowper glands. It is a clear lubricant that neutralises your urethra. It contains no sperm of its own, but sperm from an earlier ejaculation can linger in it.
In a study of 27 men, 11 of them had sperm in their pre-cum (Killick, 2011). That is 41 percent, and it is why withdrawal works so poorly.
What pre-cum is exactly and what the research says about it is in pre-cum and pregnancy.
When does a change mean something?
A sudden change that persists is more interesting than a gradual one. Think of blood in your semen, pain on climaxing, or an ejaculation that is suddenly nearly dry. Those are things to mention to your GP, not to puzzle out yourself.
The colour swings from bright white to light grey or slightly yellow. That is rarely a signal.
What strikes me here: men google about colour for weeks and hardly ever about pain. While pain is the signal that counts.
If climaxing is structurally far too fast, that is a separate topic. The median time to ejaculation in a five-country study was 5.4 minutes (Waldinger, 2005), and what that means is in premature ejaculation.
If your testicle hurts, that does not belong to an ejaculation. See testicle pain.
What can you have measured?
Ejaculation itself is not measured in blood. If you want to know something about your semen quality, a semen analysis is the only route. How to read that result is worked out in semen analysis values.
Hormones drive the production. If less drive plays along too, our overview on less interest in sex and your hormones is a logical starting point. If conceiving is not working, trying to conceive covers what you can have tested.
The IVF Partner Screening maps the blood values looked at for the man in a fertility pathway. Discuss the result with your GP afterwards.
References
- Cooper TG, Noonan E, von Eckardstein S, et al. World Health Organization reference values for human semen characteristics. Hum Reprod Update. 2010;16(3):231-245. PMID: 19934213.
- Killick SR, Leary C, Trussell J, Guthrie KA. Sperm content of pre-ejaculatory fluid. Hum Fertil (Camb). 2011;14(1):48-52. PMID: 21155689.
- Waldinger MD, Quinn P, Dilleen M, Mundayat R, Schweitzer DH, Boolell M. A multinational population survey of intravaginal ejaculation latency time. J Sex Med. 2005;2(4):492-497. PMID: 16422843.
- WHO laboratory manual for the examination and processing of human semen. World Health Organization.
Disclaimer
Caliberhealth works with BIG-registered doctors who assess your blood results. This article gives general information and does not replace medical advice from your GP or specialist. A blood test is a tool, not a diagnosis on its own. With serious complaints, contact your GP, or call 112 in an emergency.
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