Testing · 2 min read

How to read a semen analysis

The report is a wall of numbers with no explanation. Here's what each one means, what the reference ranges actually are, and what they aren't.

Any 100 sperm, at the typical line

First, scale: the count — concentration (≥16 M/ml) times volume (≥1.4 ml) — puts a typical sample in the tens of millions. The rest of the report is about quality. Take any 100 of them, at the WHO lower reference line:

Moving at all — 42 in 100

Motility. Any movement counts here, purposeful or not.

Swimming forward — 30 in 100

Progressive motility: a subset of the movers — the ones that can actually reach an egg.

Normal shape — 4 in 100

Morphology. Yes, four. Most sperm are imperfect in everyone — it's why the body makes tens of millions.

These are the WHO (2021) lower reference limits — the line under 95% of men who recently fathered a child, not the average and not a pass mark. Below a line means one thing: worth a doctor conversation, on more than one test.

A semen analysis report tells you six or seven numbers and nothing about what they mean. Here's the translation - and, more important, the right way to hold the whole thing in your head.

The numbers

Volume - how much fluid, in millilitres. Typical lab reference: 1.4 ml or more. Low volume is often just an incomplete collection or a short abstinence window, not biology.
Concentration - millions of sperm per millilitre. Typical reference: 16 million/ml or more.
Total count - concentration times volume. Typical reference: 39 million or more per sample. This is the headline number most reports lead with.
Total motility - the percentage moving at all. Typical reference: 42% or more.
Progressive motility - the percentage swimming forward rather than in circles. Typical reference: 30% or more. Forward matters; this is the one that gets sperm where they're going.
Morphology - the percentage with a typical shape, judged under strict criteria. Typical reference: 4% or more. Yes, four. Under strict scoring, almost everyone's majority is "abnormal" - the threshold is calibrated for that.
Vitality - the percentage alive, checked when motility is low. Typical reference: 54% or more.

What the reference ranges actually are

The ranges above follow the World Health Organization's current reference values, and here is the part almost nobody explains: they are the 5th percentile of men who got a partner pregnant within a year. They describe where the bottom edge of a fertile population sits. They are not a pass mark, and being under one is not a verdict - men below these numbers father children constantly, and men above them sometimes struggle.

Treat the ranges as "typical lab ranges" - context for a conversation with a doctor, not a diagnosis. No app, this one included, can tell you what your numbers mean for you. A doctor looking at the whole picture can.

One test is a snapshot

Semen parameters swing a lot - between men, and in the same man month to month. A fever eight weeks ago, a short or long abstinence window (labs ask for 2-7 days for a reason), even the stress of producing a sample on demand can move the numbers.

So the rule is: no single test is the story. Any surprising result deserves a repeat, and because sperm take about three months to make from scratch, the informative repeat is around three months later - see The three-month rule.

If your numbers came back low and you're still staring at them: read this first.