How the reaction test works
Click the pad to begin. It turns a warm colour and asks you to wait. After a pause of between one and a half and five seconds, chosen at random so you cannot learn the rhythm, it turns green. Click as fast as you can. The time between the pad turning green and your click is your reaction time, shown in milliseconds.
You can press the spacebar instead of clicking, and on a phone or tablet you tap. The clock starts in the same screen frame that draws the green pad, so the time the browser takes to draw the change is not counted against you.
Why five attempts and an average
A single reaction time is noisy. Blink at the wrong moment and the attempt is slow. Guess well and it is flattering. The test therefore takes five attempts and scores their average, and the chart shows every attempt so you can see the spread. A small spread tells you more about your reactions than one quick attempt does.
False starts and guesses
If you click while the pad is still waiting, that attempt is void and you take it again. It does not count towards the five.
An attempt faster than 100 ms is also void. Nobody reacts that quickly: it means you guessed and happened to click just after the change. The same limit is used on the running track, where World Athletics rules treat a start within 0.100 seconds of the gun as a false start.
Why the number is slower than your real reaction time
Several delays that are not yours sit between the signal and the click being recorded.
- The screen. A 60 Hz display draws a new frame every 16.7 ms, so the green pad can appear up to that much later than it was asked for, and the panel adds its own processing time on top. A 144 Hz display cuts the frame wait to under 7 ms.
- The mouse or touchscreen. A mouse reports its state at intervals, and a touchscreen takes longer than a mouse to register a press. That is why this site keeps touchscreen times apart from mouse times.
- The browser. It has to pass the click to the page. Closing other heavy tabs helps.
The result is that an online test reads higher than a laboratory measurement of the same person. Compare your scores with your own earlier scores on the same device, which is the comparison that means something.
What is a good reaction time?
Laboratory studies of young adults commonly report about 190 ms to a light. Because of the delays above, most people see a higher number here, and an average in the low 200s on an ordinary computer is fast. The rank names below are this site’s own labels, not a statement about how other people score. More on what studies report is in average reaction time.
| Rank | Average of five |
|---|---|
| Falcon | under 180 ms |
| Cheetah | 180 to 209 ms |
| Fox | 210 to 239 ms |
| Rabbit | 240 to 279 ms |
| Turtle | 280 to 339 ms |
| Sloth | 340 ms and over |
Other reaction tests
- F1 reaction test: five start lights come on one by one and you react when they go out.
- Sound reaction time test: react to a beep instead of a colour. Most people are faster to sound.
For finger speed rather than reaction speed, try the CPS test.