Understanding Your Reaction Time
Reaction time is the interval between noticing a signal and responding to it. In this test, the signal is a sudden green panel and the response is your click, tap, or key press. The displayed result is measured in milliseconds, where 1,000 milliseconds equals one second.
The wait before each green signal is randomized at runtime. Some rounds begin relatively quickly, others take a medium amount of time, and some take longer. This variation helps prevent you from learning a fixed rhythm and reacting before you actually see the signal.
Results can vary with alertness, practice, input hardware, display refresh rate, browser performance, and whether you use a mouse, touchscreen, or keyboard. For useful comparisons, complete all five valid rounds under similar conditions and focus on the summary rather than a single unusually fast or slow result.
This browser test is designed for casual self-measurement and practice. It is not a medical, neurological, or fitness assessment.
Private Browser Processing
The timer and results run entirely in your browser. Your reaction-time attempts are not uploaded or saved by this tool.