Reaction Time Test

How to use it

1. Press the area to start round 1. It turns red.
2. Wait for the area to turn green, then press or click at once.
3. Read the reaction time shown under the area, then press to start the next round.
4. After five rounds, read Average, Best and Slowest, and compare them with the reference.

What the test measures

It measures the time from the moment the area turns green to your press. This is a simple reaction: you know what to do and only have to respond. The figure includes the time the screen takes to show the green and the time your device takes to send the press, so it is a little longer than the nerve signal alone. The page reads the clock again on the frame after green appears, so the result can be off by about one frame, roughly 16 ms on a 60 Hz screen.

Why the wait is random

The wait is between 1.5 and 5 seconds. It is drawn with the browser's secure random number generator, so you cannot predict the colour change from a rhythm. A press while the area is red counts as too early, and that round starts again.

The reference figure

The comparison uses 190 ms, the figure the Wikipedia article on reaction time gives for detecting a visual stimulus in college-age people. Averages change with age, tiredness, the device and the test itself, so treat the comparison as a rough guide.

What it does not measure

Reaction to a sound, a touch or a moving target differs from a reaction to a colour, and so does reaction in a game. A web page cannot give a medical reading.

Frequently asked questions