Benchmento is a small, independent site hosting short tests that measure reflexes, motor speed and working memory. It exists because the standard versions of these tests are usually a white page with a blue button, and because a raw score with no comparison attached is not very interesting.
How the tests are measured
Every test runs entirely in your browser using the high resolution timer available to JavaScript. Nothing is timed on a server, so network latency never enters a result. What does enter a result is your own hardware: display refresh rate, input device polling, and browser scheduling all contribute a small and mostly constant offset. This is why the reaction time test averages five attempts instead of reporting a single click.
Where the percentiles come from
Each test carries a distribution curve assembled from published ranges for that task, anchored at a series of score and percentile pairs with linear interpolation between them. The percentile answers what proportion of the general population you would expect to beat. It is not a ranking against other visitors to this site, who are a self-selecting group and would produce a misleading comparison.
These curves are indicative rather than clinical. They are good enough to tell you whether you are above or below typical, and not precise enough to distinguish the 71st percentile from the 74th.
Your data
There are no accounts and no score uploads. Personal bests live in your browser's local storage on the device you played on. Clearing site data clears them. The site uses analytics and advertising, both of which are described in the privacy policy.
Supporting the site
Benchmento is free and has no paid tier. It is funded by advertising placed well away from anything you click during play, and by people who choose to buy the developer a coffee. Neither affects what the tests measure or what they report.
Corrections
If a score curve looks wrong, a test misbehaves on your device, or a page has an error in it, the contact page is the place to say so. Bug reports that include your browser and device are the most useful kind.