Reaction Time Test

about this tool

Wait for green, then tap

Tap the panel to start. It goes grey while it waits, turns green at a moment you cannot predict, and times you from the green to your tap. Tap too early and the round is thrown away rather than counted.

The panel itself is the control, so you can keep tapping the same place rather than moving between a button and a target, which would time your aim as well as your reaction.

Why the wait is random

The delay is drawn fresh each round, between 1.2 and 5 seconds, from the same fair source the rest of these tools use.

This matters more than it looks. A fixed wait, or a short one, can be anticipated: you tap on a rhythm and score a number that has nothing to do with reacting to anything. With the wait unpredictable and never shorter than a second, an early tap is a false start rather than a good score, and it is treated as one.

What the number actually includes

A browser can only time from when it painted the green to when it was told about your click. Both ends carry delays that are nothing to do with you:

• A 60 Hz screen shows the change up to 17 ms after the page asked for it, and more if the compositor is busy.
• A mouse or keyboard has its own polling and debounce delay, typically another handful of milliseconds, and Bluetooth adds more than a cable.
• A busy page, a heavy tab in the background, or a laptop in a power-saving mode will all add their own.

So the figures here read slower than laboratory results for the same task, and comparing your number against a friend's means comparing two sets of hardware as much as two people. Comparing your own attempts on the same machine is the part that means something.

What it is not

It is not a measure of anything about you beyond this minute: not your health, not your age, not your ability to drive. It is a browser reacting to a mouse. The figures on screen say how you did at tapping a panel today, and the wording never claims more than that.

Nothing is stored between visits. The last 25 attempts stay on screen and can be copied, and a refresh clears them.

For the other half of the same question — how fast you can repeat a click, rather than how fast you can start one — see clicks per second.

questions

What is a good reaction time?

On a browser test, 200 to 300 ms is where most people land and under 200 ms is genuinely fast. These numbers run slower than laboratory figures for the same task, because a page can only measure from when it painted to when it was told about the click.

Why is the wait before green different every time?

So it cannot be anticipated. A fixed wait measures your guessing rather than your reacting, and it is easy to score absurdly well by tapping on a rhythm. The delay is drawn fresh between 1.2 and 5 seconds each round.

What happens if I tap early?

It is caught and thrown away rather than counted. A false start does not join your average, and the round restarts.

Does my screen affect the result?

Yes, and so does your mouse or keyboard. A 60 Hz screen adds up to 17 ms before you see the change, and input hardware adds more. Tens of milliseconds of any result here belong to the equipment rather than to you.

Are my scores saved?

No. The last 25 attempts stay on screen and can be copied, but nothing is stored on your device and a refresh starts again.