Reaction time test
Wait for green, then click. Five goes, then an average.
- Runs in your browser — nothing you enter is uploaded
- No sign-up, no quotas, free to use as often as you like
How it works
A single attempt tells you very little — reaction time varies a lot from go to go. Five attempts and an average is the smallest sample that means anything, which is why the test runs that way rather than giving you one dramatic number.
The wait is random
The delay before green is random between one and four seconds, so it cannot be anticipated. If you click during the wait it is recorded as a false start and does not count — otherwise the test would simply reward guessing.
What the numbers mean
For a visual signal and a mouse click, most people land between 200 and 300 milliseconds. Under 200 is quick. The figure includes far more than your nervous system: the monitor's refresh interval, the mouse's polling rate and the browser's own frame timing all add several milliseconds each, so treat the number as your reaction plus your equipment.
Why your score drifts
Reaction time is sensitive to tiredness, caffeine, alcohol, how warmed up you are and how much you are concentrating. Comparing your own scores across a day is more informative than comparing yourself with anyone else.
How it is measured
Timing uses the browser's high-resolution clock, which is accurate to well under a millisecond — the uncertainty is in the display and input hardware, not the measurement.
Reaction time test — questions
What is a good reaction time?
Between 200 and 300 milliseconds is typical for a visual signal and a mouse click. Under 200 is fast.
What happens if I click too early?
It is recorded as a false start and does not count towards your average.
Why is my time slower than I expect?
The measurement includes your screen's refresh interval and your mouse's polling rate, which can add 10 to 30 milliseconds before you have done anything.
How many attempts does it take?
Five, then it reports your best and your average.
Is my score sent anywhere?
No. Everything stays in your browser.