Words per minute and clicks per minute are both rates over a fixed interval, and that similarity is where the comparison should stop.
The measurements are shaped differently
A typing test measures a sequence with a correctness condition. Every keystroke has a right answer, and the standard unit is deliberately synthetic: a “word” is five characters including the space, so WPM is characters ÷ 5 ÷ minutes. Accuracy is not a bonus statistic — an error changes the score.
A click test measures a repetition with no correctness condition. There is one target, it never moves, and no press can be wrong. All that remains is rate.
That is why a click test can report a meaningful number from one second of input and a typing test cannot.
What each one is limited by
| Typing | Clicking | |
|---|---|---|
| Limiter | Sequence planning | Muscle reset time |
| Fatigue onset | Minutes | ~6–20 seconds |
| Hardware effect | Small | Large |
| Useful interval | 60 s+ | 1–60 s |
Typing is bounded by how fast you can decide what to press next. Clicking is bounded by how fast one switch can be reset. Practice moves them by different mechanisms, and being good at one predicts almost nothing about the other.
The one place they meet
Both are worth measuring on the same clock and reporting with their interval attached — and both are ruined by the same thing, which is comparing a number against a number taken under different conditions. A 90 WPM figure on familiar prose is not a 90 WPM figure on random words, in exactly the way a 600 CPM one-second burst is not a 600 CPM minute.