Hit it the moment
it turns yellow.
Five rounds. The wait before each one is random, so you cannot guess it — and if you hit early, that round is a foul and does not count towards your time. Then we take your number apart and show you how much of it was never you.
—Fastest clean round
—Middle of your five
—Fastest to slowest
—Hit before it lit up
Finish five rounds and this fills in with what your own numbers say.
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Some of that was the screen
Your screen does not light up the instant the code says to. It waits for its next refresh — and we are timing yours right now, from the real gaps between frames on this page.
Screen waiting to repaint
Everything else, which includes you
This splits your fastest clean round. It is an upper bound on the screen’s share, not a measurement of your brain.
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What this actually measured
- The clock starts when the pixels change, not when the code decides to change them. We take the timestamp inside the browser’s own paint callback, so the wait for the next refresh is included in your number rather than hidden from it.
- The wait is random, between 1.2 and 4.2 seconds, redrawn every round. Without that you would be timing your prediction, not your reaction — which is why hitting early is recorded as a foul instead of a very fast round.
- Fouls do not count towards any figure above. They are shown because a run with three fouls in it is a different run from a clean one, and hiding them would flatter you.
- The middle number is the median, not the average. One bad round — a notification, a sneeze — drags an average of five a long way. The median barely moves.
- The refresh figure is measured, not looked up. We time the gaps between real frames on this page and take the middle one. A 60 Hz screen lands near 16.7 ms, a 120 Hz one near 8.3 ms, but the number you see is yours.
- Nothing here is a clinical measurement. A mouse, a trackpad and a touchscreen all report at different rates, a busy laptop adds delay, and this is one browser tab among however many you have open. Compare your rounds to each other, not to anyone else, and do not read anything medical into them.