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Reaction Tester

Test your reaction time with millisecond precision. Click as fast as possible when the screen turns green. Average and best times tracked locally.

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How is reaction time measured?

Reaction time is the interval between a stimulus appearing (the green flash) and your motor response (your click). The browser measures this with performance.now() for sub-millisecond precision. Average human reaction time to a visual cue is around 250 ms. Athletes and gamers often score in the 180–220 ms range.

Common uses

  • Fitness check — track your reflexes over time.
  • Gaming benchmark — see how you compare to esports averages.
  • Fatigue test — detect when you're too tired to drive or work.
  • Fun challenge — race friends and family.

Privacy

All timing runs 100% in your browser. No data is sent to any server.