Reaction Test
Wait for green, then tap as fast as you can. Five goes, averaged. The number you get is more interesting than it first looks, and the explanation below tells you why.
How to play
Tap the panel to arm it. It turns red and holds for a random interval between roughly one and three and a half seconds. When it turns green, tap as fast as you can. Tap while it is still red and the attempt is void.
The delay is deliberately random. If it were fixed you would learn the timing and start anticipating, which measures rhythm rather than reaction.
You can also use the space bar, which is generally slightly faster than a mouse click.
What your number actually means
Simple visual reaction time in adults typically falls somewhere around 200 to 270 milliseconds on a screen based test like this. Below 200 is quick. Above 300 is on the slower side without being unusual.
| Average | Roughly |
|---|---|
| Under 180ms | Exceptionally fast, or you anticipated |
| 180 to 220ms | Fast |
| 220 to 270ms | Typical range |
| 270 to 330ms | A little slower than average |
| Above 330ms | Slow for this test, often tiredness or the device |
Where the time actually goes
Your 250 milliseconds is not one process. It is roughly: light reaching your retina and being transduced, the signal travelling to the visual cortex, recognition that the colour changed, a decision to move, the motor command travelling down to your hand, and the muscle actually contracting. The purely biological floor for a simple visual response is somewhere in the region of 150 milliseconds and cannot be trained away.
Then there is the equipment. Your screen refreshes at a fixed rate, commonly 60 times a second, so on average about 8 milliseconds pass between the colour changing in software and your eye seeing it. Touchscreens add input latency of their own. A slower phone can easily add 30 to 50 milliseconds that have nothing to do with you.
This is why comparing your result against someone on a different device is not very meaningful. Comparing your own result across days on the same device is.
Why five attempts and not one
Reaction time is noisy. Any single attempt can be 40 milliseconds off your true baseline through nothing but chance, so a single number tells you very little. Averaging several is the minimum needed for a figure worth looking at, and five is a reasonable compromise between accuracy and patience.
If you want a genuinely stable measure, take three sets of five on the same device at the same time of day and use the middle result.
What changes your reaction time
- Sleep. The largest single factor by some distance. One badly short night can slow simple reaction time noticeably, and the effect compounds across several.
- Time of day. Most people are fastest in the late morning and again in the early evening, with a dip in the early afternoon.
- Age. Simple reaction time is generally quickest in the late teens and twenties and slows gradually after that. The decline is real and modest.
- Caffeine. A small genuine improvement, usually a few milliseconds, and considerably less than a good night's sleep.
- Anticipation. If you start guessing the timing you will produce faster numbers that mean nothing, and occasionally a void attempt.
- Alcohol and fatigue, both of which slow it measurably, which is the practical reason this matters at all.
Simple against choice reaction
This test measures simple reaction time: one signal, one response, no decision about which. Choice reaction time, where you must pick between responses, is substantially slower, typically by 100 milliseconds or more, because it adds an actual decision step.
That distinction matters for anything real. Braking when a light turns red is close to simple reaction. Deciding whether to brake or steer around an obstacle is choice reaction, and it is much slower. Most of what people call "quick reflexes" in driving or sport is really trained pattern recognition, which shortens the decision rather than the reaction.
Your best time is stored in your browser on your own device and never uploaded.
Common questions
What is a good reaction time?
On a screen based test, 220 to 270 milliseconds is the typical adult range. Under 200 is fast. Above 330 usually says more about tiredness or the device than about you.
Why does my phone give a slower result than my laptop?
Screen refresh rate and touch input latency both add real milliseconds before your tap is registered. A slower device can easily add 30 to 50 milliseconds. Compare your results on the same device across days rather than across devices.
Can I train my reaction time to be faster?
Only slightly. The biological floor for a simple visual response is around 150 milliseconds and cannot be trained away. Practice on a specific task helps mainly by removing hesitation and by improving anticipation. Sleeping properly will do more for your number than practising will.
Why does the delay before green vary?
So you cannot learn the timing. A fixed delay would let you anticipate, which measures rhythm rather than reaction and would produce meaninglessly fast results.
Why does tapping early not count?
Because a response before the signal is not a reaction to anything, it is a guess. Counting it would let anyone produce a very fast average by tapping continuously.
Is this the same as the reaction time used in driving tests?
No. This is simple reaction time, one signal and one response. Driving mostly involves choice reaction, where you decide between responses, and that is typically 100 milliseconds or more slower.