When men think about sperm health, the figure that usually comes to mind is the count. Yet motility, the proportion of sperm that actually move, is arguably just as important, and it has become a focus of recent research. A 2024 study of donor candidates, indexed on PubMed, found that motile sperm concentration fell by around 16% and total motile sperm count by around 22% between 2019 and 2022, even though overall sperm concentration in the same group did not change significantly. Findings like these have helped push motility from a technical footnote into a parameter that men increasingly want to understand for themselves.

That interest has met a growing market of at-home tests that promise to measure not just whether sperm are present, but how well they swim. Biohacker, and longevity expert Bryan Johnson has made his lifestyle around sperm health. This article explains what sperm motility is, what the reference numbers actually mean, how home motility tests work, and where they sit alongside a clinical semen analysis.

What sperm motility actually is

Motility is the share of sperm in a sample that are moving. Clinically, as patient guidance from the British Association of Urological Surgeons puts it, it describes the “swimming ability” of sperm, and it is measured as part of a standard semen analysis alongside count and shape.

The measurement is usually split into two types. Total motility counts any sperm that move at all. Progressive motility counts only the sperm that swim forward in a broadly straight line or in large circles, the kind of purposeful movement associated with travelling towards an egg. Because progressive movement is more relevant to natural conception than mere twitching on the spot, many tests and clinicians pay particular attention to it.

The reference values, and why they vary

One source of confusion for anyone reading their own result is that the “normal” thresholds quoted by different sources do not always agree. This is not an error so much as a reflection of how reference ranges have been defined and revised over time.

BAUS patient guidance describes a typical threshold of more than 30% of sperm moving. UK consumer guidance from Clearblue, drawing on WHO-based figures, describes normal total motility as roughly 40% to 81% and cites progressive motility of 32% or more as within the normal range. These different cut-offs exist because the underlying reference ranges have been revised across editions, and public-facing sources sometimes quote different vintages. The practical takeaway is that a single percentage means little without the context of which reference set it is being compared against.

It also helps to see motility as one number among several. A full semen analysis, as the NHS describes it, looks at how many sperm there are, how well they move, and their shape. Motility on its own is informative, but it is read in combination with concentration and the other parameters, not in isolation.

Why motility, not just count, has drawn attention

The renewed focus on movement rather than sheer numbers is partly a research story. The 2024 donor-candidate study mentioned above is striking precisely because the motility-based measures fell while raw concentration held steady, suggesting that movement may capture changes that a simple count misses.

The wider picture is genuinely contested, which is worth stating plainly. Some widely cited analyses, including a 2022 review in Nature, have reported long-run declines in sperm count of well over half across several decades in men from Western countries. Other researchers disagree: a 2024 University of Manchester summary concluded that the widely held view that sperm counts are falling globally “may be wrong.” Against that unsettled backdrop, motility has become an appealing thing to measure because it is responsive, informative, and, as it happens, more practical to assess outside a laboratory than some other parameters.

How at-home sperm motility tests work

Home motility tests generally take one of a couple of approaches, and the difference matters for what you get back.

Threshold and cartridge tests

Some kits use a disposable cartridge or device that estimates the proportion of moving sperm against a fixed benchmark, returning a colour-coded or above/below reading. One widely sold UK product, for example, measures progressive motile sperm cells and reports a result through a colour change, with the sample left to process across two short waiting periods. Manufacturers of these tests often publish performance figures: the same product cites sensitivity of 96% and specificity of 91% against its threshold.

Smartphone and optical analysis

The more advanced approach uses a small optical module or smartphone camera to capture the sample and software to estimate the proportion of moving and progressively moving sperm. These systems can report several parameters at once, often including volume, concentration, motility, and total motile sperm count, and many store results in an app so that change can be tracked across samples. They cost more than a single threshold test, but they answer more questions and support repeat measurement.

Why timing and handling matter

Whichever type you choose, the conditions of the sample shape the result. Most protocols recommend an abstinence period of around two to seven days before testing, analysing a fresh sample promptly, and keeping the collection method consistent between tests. Get those wrong and even an accurate device will produce a noisy reading, which is a common reason home results and clinic results diverge.

How accurate are home motility tests compared with a lab?

The honest answer is that home motility tests are screening tools, not diagnostic ones. The NHS describes laboratory semen analysis as checking count, movement, and shape under controlled conditions, which is broader than what most consumer kits do. A home test can give a useful indication of whether motility is broadly typical or potentially low, but it does not replace a clinical analysis.

Published accuracy figures vary by device and describe agreement with a specific reference under specific conditions. The threshold cartridge test cited above reports sensitivity of 96% and specificity of 91%; some app-based systems quote agreement above 95% when compared with laboratory equipment. Encouraging as those numbers are, they are not a promise about an individual’s fertility. A result outside the normal range is best treated as a reason to seek a clinical opinion, not as a diagnosis.

What to look for in a home motility test

If you have decided that motility is what you want to measure, a few features separate a useful kit from a limited one.

Does it report progressive motility?

A test that reports progressive motility, rather than only a single above-or-below count reading, gives you more of the information clinicians actually use. If movement quality is your concern, that distinction is worth checking before you buy.

Independent validation

Look for a CE mark, which indicates the device meets the relevant requirements for sale, and for evidence that the manufacturer takes part in external quality-assessment schemes such as UK NEQAS. Independent evaluation against laboratory reference methods is a meaningful signal that the numbers can be trusted within their stated limits.

Repeat testing built in

Because motility fluctuates between samples, a single reading can mislead. Kits that include more than one test, and an app to track results, let you look at a trend rather than a one-off figure, which is closer to how andrology services interpret results in any case.

An example of the multi-parameter, app-based approach is ExSeed Health, a UK-facing brand whose system measures volume, concentration, motility, and total motile sperm count and returns a fertility score through a paired app in around 15 minutes. ExSeed reports agreement of more than 95% compared with advanced laboratory equipment, and states that its device is CE marked and has been independently validated through external UK NEQAS quality control. The company says its kit has been used by more than 65,000 men and sells it in multi-test packs so that, in line with the general advice to test more than once, users can repeat the measurement. For men who specifically want a tracked home sperm motility test rather than a single threshold result, that multi-measurement format sits at the more detailed end of the consumer market.

When to move from home screening to clinical testing

A home motility test is a reasonable way to gather an early, private indication, or to monitor change over time. It is not a substitute for medical assessment. NHS guidance suggests speaking to a GP after around a year of trying to conceive without success, or after six months if the female partner is 36 or over, or sooner if there is a known reason for concern.

A home result outside the reference range, or any persistent concern, is a prompt to arrange a formal semen analysis through a GP referral. It is also worth remembering that fertility is a two-person picture: a semen test, at home or in a clinic, cannot speak to female factors, which a full couple assessment would consider. A result within the normal range is reassuring but does not rule everything out, and a single low figure is generally not interpreted on its own in clinical practice.

The takeaway

Sperm motility has earned its place alongside count as a measure worth understanding, and at-home tests now make it possible to get an early read on movement without a clinic visit. Used sensibly, they can give a helpful first data point: choose a kit that reports progressive motility, carries a CE mark and credible external validation, and lets you test more than once. Then read the result for what it is, a screening signal rather than a verdict. A reassuring number is encouraging, an unexpected one is a reason to speak to a GP, and neither replaces the laboratory semen analysis that remains the clinical standard.