How it works
Start arms a random 1–5 second wait; the pad flips from red to green and the clock starts. Your click stops it to the millisecond, and the board keeps your best and average across tries.
red → green → click → milliseconds
Tips
- Rest your finger on the pad and watch with soft eyes — chasing the change slows you down.
- Take 5 tries and trust the average, not one lucky hit.
- Everything runs in your browser; nothing is uploaded.
Standards and sources
- Woods DL et al. (2015), Factors influencing the latency of simple reaction time — Front Hum Neurosci (PMC, NIH)
- Jain A et al. (2015), A comparative study of visual and auditory reaction times — Int J Appl Basic Med Res (PMC, NIH)
- W3C — High Resolution Time (performance.now)
Last reviewed October 13, 2026
Frequently asked questions
What is a good time?
Most people land between 200 and 300 ms. Under 200 is quick; under 150 usually means you anticipated it.
Why did it say too soon?
Clicking before green restarts the round — that keeps guesses from counting as reactions.
How is it timed?
With the browser’s high-resolution clock on your device. Nothing is sent anywhere.