What Is the Fastest Human Reaction Time?

There is no official world record for human reaction time, because the result depends on the signal, the task and the equipment used to measure it. The best evidence for the human limit comes from sprint starts, where research found that some athletes can react to the starting signal in under 100 milliseconds.

Most people are much slower than that. A large lab study of simple visual reactions found an average of about 213 ms once equipment delays were removed.

The limit: sprint starts

Sprinting is one of the few places where reaction time is measured precisely in competition. Starting blocks at major championships contain sensors that record how quickly each athlete pushes off after the gun.

World Athletics treats any reaction faster than 0.100 seconds after the gun as a false start, on the basis that nobody can genuinely react that fast. Researchers have questioned that assumption. In a 2007 study, Pain and Hibbs measured sprint starts with force sensors in the blocks and found:

• Five of the nine athletes had average reaction times under 100 ms in at least one test condition.
• About 20% of starts in the first two conditions were faster than 100 ms.
• The neuromuscular part of the reaction could be faster than 85 ms.

So the human limit for reacting to a sound with a well-trained movement seems to sit somewhere below 100 ms, at least occasionally.

Why sound beats sight

Studies comparing the two generally find people react faster to sounds than to lights. A sprinter reacts to a gun, which is one reason sprint starts can be so quick. Visual reactions, like clicking when a screen changes colour, are usually slower. Compare your own results on the visual and audio tests, and read visual vs auditory reaction time.

A fast start isn't everything

When Usain Bolt set the 100 m world record of 9.58 seconds in Berlin in 2009, his official reaction time was 0.146 seconds. That was only the sixth fastest reaction in the final, yet he still won clearly. Reaction time matters, but in most sports it's one part of performance, not the whole story.

What about online tests?

On an online test, your result includes your own reaction plus the delay of your screen, mouse or touchscreen, and browser. That usually adds tens of milliseconds, so online scores are slower than lab results. See mouse latency and reaction time.

Very fast online scores are also easy to fake by accident. If the wait before the signal is random, a click under about 100 ms is almost always a guess that happened to land at the right moment. That's why our tests don't count responses that are too fast to be genuine.

How fast are you?

Take the reaction time test a few times and look at your average and median, not just your best click. Then see what is a good reaction time and the average reaction time page to see how you compare. If you want to get faster, start with the how to improve reaction time guide.