What clicks per second actually measures
Clicks per second is exactly what it sounds like: the number of button presses you register in one second, averaged over the length of the run. The number matters in a narrow set of games — Minecraft PvP, where hit rate is tied to click rate, and RTS titles where unit micromanagement rewards fast input — and matters almost nowhere else. It is worth being clear about that up front, because CPS scores get treated as a general measure of skill and they are not one.
Normal clicking with one finger lands somewhere between 4 and 8 CPS for most people. Anything much above that is not faster finger movement; it is a different physical technique. Jitter, butterfly and drag clicking each produce far more actuations per second than a single finger can, and each puts a different kind of load on your hand. Those techniques are explained below, along with the reason a very high score sometimes says more about your mouse than about you.
The run length changes what you are measuring. A one-second burst captures peak rate and almost nothing else — reaction time and the moment you happen to start dominate the result. Five seconds is the usual benchmark because it is long enough to average out a lucky start. Ten and fifteen seconds measure stamina, and most people watch their rate fall noticeably across the run, which is the more honest number if you care about sustained performance rather than a personal best.
If you came here to test a keyboard rather than a mouse, two other tools fit better. The spacebar counter counts space bar presses specifically and filters out auto-repeat from a held key, which a click counter cannot do. If a single press is registering twice, that is switch chatter rather than speed, and the double typing test measures the millisecond gap that proves it.