Five goes. The middle one counts, not the luckiest.
The wait is random between 1 and 3.5 seconds, so it cannot be learned.
Your best median in this browser: —
A 60 Hz panel refreshes every 16 milliseconds, so the green may already exist while your eyes are still shown the old frame. A slow panel adds a few more on top.
Next step: Compare only on the same screen. If you want the number lower, a faster display does more for it than practice does.
A wireless mouse reporting at 125 Hz spends around 8 milliseconds getting the click to the computer; a fast wired one, about one. A trackpad adds more than either.
Next step: Use a wired mouse for the number you intend to quote, and treat trackpad results as their own separate scale.
The part that is actually yours is roughly 150 to 250 milliseconds, and it moves with sleep, caffeine, illness and how long you have already been staring at the screen.
Next step: Run five attempts twice at different times of day. The gap between the two runs tells you more about yourself than either number alone.
| Approach | Best for | Trade-off |
|---|---|---|
| This page | Anyone who wants a number for their own eyes and hand, on their own screen | The screen and the mouse are inside the measurement, and together they can account for 30 to 50 milliseconds |
| A reaction test inside a game | Players comparing themselves in the setting they actually care about | The game engine adds its own frame of delay, and each game adds a different one |
| A ruler dropped between the fingers | Anyone without a computer, and it is the classic classroom method | Measures a different thing — catching a falling object — and depends heavily on how the ruler was held |
| Laboratory equipment with a hardware button | Researchers who need the person separated from the hardware | Not available to you, and the reason its numbers are lower than anything a browser can report |
Where this stops being the right tool — and what to use instead.
A 60 Hz screen adds up to 16 milliseconds of waiting before the green even appears, a 144 Hz screen about 7. Wireless mice add a few more. The gap between two setups is often bigger than the gap between two people.
Next step: Compare on the same machine, one after the other. That removes the hardware from the question and leaves the part you meant to measure.
This is a page in a browser. It cannot separate attention, tiredness, caffeine, screen delay and genuine impairment, and every one of those moves the number by more than the effect you would be looking for.
Next step: Talk to a doctor. Bring the observation that something changed if you like, but do not bring a screenshot of this page as evidence.
The wait is randomised precisely because a fixed delay can be learned. Guessing produces impossibly low numbers, and any figure under about 100 milliseconds is a guess that happened to land.
Next step: Let the false start stand and take the attempt again. A result built from guesses measures your luck, not your reflexes.
A single attempt swings by a third for the same person on the same day. That is why this page takes five and shows the middle one.
Next step: Run the full five, and if you want a real comparison, run it twice more at different times of day. The spread between runs is itself informative.
