Free reaction time test — instant play, no signup, no download
Reflex Test measures how fast you respond to a signal. It is a simple reaction task, and the important thing to understand about it is that hardware contributes real milliseconds — so the number is only meaningful against your own history on the same device.
Wait for the signal.
Respond the instant it appears.
Early responses are rejected.
Several trials are averaged.
Your result is the average in milliseconds.
Simple reaction speed. It varies with alertness, sleep, caffeine and time of day by more than most people realise, and by more than practice moves it.
Hover rather than rest.
Do not anticipate. Random delays make anticipation a losing strategy.
Test at the same time of day when comparing. Reaction time follows a daily rhythm.
Average multiple trials. Single results are dominated by noise.
Same underlying measure, different presentation. Both are simple reaction; use whichever you prefer and stick with it for comparison.
Stimulants reliably shorten reaction times somewhat in the short term. It is one of the more robust findings in the area.
Anything much under that on a normal setup usually means you anticipated rather than reacted — physiology plus display latency makes it very difficult honestly.
Touchscreen polling and display latency both add time. It is a hardware difference, not a difference in you.