Reaction Time Test

What is a reaction time test?

A reaction time test measures how quickly you respond to a visual stimulus. Your reaction time is the delay between seeing a signal and physically responding to it, typically between 150ms and 300ms for most people.

This test uses high-precision browser timing (performance.now()) synchronized with requestAnimationFrame to give you the most accurate measurement possible in a web browser. It runs 5 trials and reports your median time: the middle value, which filters out lucky or unlucky outliers.

What's a normal reaction time?

For a simple visual stimulus like a colour change, most adults react in about 200-250 milliseconds. That number comes from over a century of lab research: Welford's 1980 review of the literature placed average visual reaction time at 180-200ms, and more recent large-scale studies like the Baltimore Longitudinal Study of Aging (1,265 participants aged 17-96) confirm the range. Sound is faster: auditory reaction time averages about 140-160ms because sound reaches the brain in 8-10ms, while light takes 20-40ms.

Your result depends on more than just reflexes. Age, sleep, caffeine, device type, and even which hand you use all affect the number. A 2015 review in Frontiers in Human Neuroscience catalogued over a dozen factors that shift simple reaction time by 10-50ms each.

How fast are the fastest humans?

Formula 1 drivers~200 ms

On average, drivers launch their cars about 0.2 seconds after the lights go out, according to Formula 1.

Olympic sprinters166-189 ms

At the 2008 Beijing Olympics, sprinters reacted to the starting gun in 166ms on average for men and 189ms for women. World Athletics rules a false start under 100ms, assuming anything faster is anticipation, not genuine reaction.

Pro gamers~220 ms

In a 2023 lab study, professional Counter-Strike players averaged 219ms on a simple mouse-click test, against 271ms for inexperienced players. That's a 52ms gap.

Fighter pilots~200 ms

Around 200ms for simple visual stimuli under normal conditions, though reaction time degrades under high G-forces. A 2013 study in Aviation, Space, and Environmental Medicine measured measurable slowing at +4.5G sustained acceleration.

Does reaction time change with age?

Yes. The Baltimore Longitudinal Study of Aging tracked over 1,200 people and found that simple reaction time slows by about 0.5ms per year starting from your early twenties. That means a 65-year-old is roughly 20-25ms slower than they were at 20, not a dramatic change in everyday life, but measurable in a precise test like this one. More complex tasks (like go/no-go) slow faster, at about 1.6ms per year.