Reaction Time Test
Click the moment the screen changes colour. Your last ten results and their average are saved, and an average of five can be sent to a friend as a challenge.
Average of last 10: -
Whoever opens the link sees your average of five and plays the same way.
How to use the Reaction Time Test
- Click the box once to arm the test. Its colour changes and it asks you to wait for green.
- Between one and four seconds later the box turns green and reads click now.
- Click at that moment. Your time in milliseconds appears under the box.
- Clear records empties the list and the average shown beside it.
- After five rounds you get an average of five, and Send a challenge makes a link your friend can play against.
The wait is random between one and four seconds
The delay is drawn fresh each round inside that window. A fixed wait would let you count the rhythm and press without watching. Clicking before the green appears counts as a false start, and that attempt is not added to your records.
Fifty attempts stored, ten in the average
The average covers your ten most recent attempts, with the number used printed beside it, so it appears after the first go. Up to fifty attempts are kept in this browser's local storage on this device, and clearing site data removes them.
Challenge a friend
Once you have taken five rounds, your average of five and your fastest time appear under the box along with a Send a challenge button. Add a nickname if you like and press it: a phone opens the share sheet, and a computer copies the link. Your friend sees your score at the top of the page, takes five rounds of their own, and the page shows who won and by how many milliseconds.
The lower average wins, and a tie on the average goes to the faster single time. One round depends a lot on luck, which is why the challenge uses five. Nothing is stored on a server: the score travels inside the link. A mouse and a touch screen respond differently, so the result says so when the two players used different devices.
Times are taken from the moment you press down on the box. Anything under 100 milliseconds is treated as a guess made before the colour changed and is left out of your records.
Frequently asked questions
What is a normal reaction time?
Most people fall between 200 and 300 milliseconds for a visual signal. Reaction times lengthen with fatigue and with age.
What if I click too early?
Clicking before the colour change counts as a false start and you can try again.
Are my results saved?
Yes, in your browser, so your recent scores and average are still there when you return.
Does my time include screen and mouse lag?
Yes. The clock starts when the page paints the green box, so display refresh and input handling sit inside the figure. A 60 Hz screen alone can add up to about 16 milliseconds.
Can I use the spacebar instead of clicking?
No. Only a click or a tap on the box registers, so a keyboard press does nothing to start or to stop the round.
What happens once I pass fifty attempts?
The oldest entries drop off the stored list. The average is unaffected, since it only ever reads the ten most recent times.
How do I challenge a friend?
Take five rounds, then press Send a challenge to share the link. When your friend finishes five rounds, the lower average wins and the gap in milliseconds is shown.
Why was a time under 100 ms not counted?
A time that short comes from pressing before you could have seen the colour change. It is left out of the list, the average and the challenge score, and you are asked to try again.