Reaction Time Tester
A clean, free, browser-based tool for measuring your reaction time. Five rounds, percentile ranking, automatic history — no sign-up, no install.
What is a reaction time tester?
A reaction time tester is any tool — software or hardware — that measures the latency between a stimulus and your response. The web-based version you are looking at right now uses a colour change as the stimulus and a mouse click or screen tap as the response. Lab versions use light sensors, auditory cues, and electromyography to break the response down into its component parts: nerve conduction, cortical processing, and motor output.
The accuracy of a browser-based tester surprises most people. Modern browsers expose a high-resolution performance API (performance.now) that is accurate to microseconds — far beyond what any human could perceive. The timing of the test itself is essentially perfect. The main source of error is the hardware between the browser and your body: monitor refresh rate, mouse polling rate, and input debouncing all add a few milliseconds of latency that the test cannot subtract.
For most people, this does not matter. As long as you use the same device each time, your scores will be comparable across sessions. If you want to push for your absolute lowest number, use a wired gaming mouse (1–2 ms latency), a 144 Hz or faster monitor (7–16 ms less latency than 60 Hz), and a wired keyboard if you prefer clicking with the spacebar.
Why use a reaction time tester at all?
People test their reaction time for a mix of reasons. Gamers want to track their baseline and see if practice is paying off. Athletes use it as a quick check on fatigue and recovery. Older adults use it to monitor age-related slowdown. Some people test out of pure curiosity — they have heard claims about 150 ms esports pros and want to know where they sit.
Whatever your reason, the key thing to remember is that single results are noisy. Your score on any given attempt can swing by 30–50 ms for no obvious reason. The five-round trimmed average we use here is far more stable. And if you are tracking changes over time, test under the same conditions each session — same time of day, same device, same lighting — to minimise noise.
Once you have your number, head over to our average reaction time page to see where you sit relative to the wider population, or check the by-age breakdown if you want a more age-specific comparison.