Reaction Time Test
Tap when it turns green. Five rounds: the average is your score.
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Bar widths show roughly how many people land in each band; the middle is crowded. Five runs, averaged: one click can get lucky, five can't.
What moves it
Your hardware. A 60 Hz screen adds real milliseconds a 144 Hz screen doesn't. Touchscreens read slower than mice.
Sleep and caffeine. A short night is worth tens of milliseconds. Caffeine buys a few back.
Age and practice. Peaks in your early twenties, drifts up slowly after. Practice trims the fat but can't beat biology.
What this measures
Simple reaction time is the shortest loop your nervous system runs: one signal, one response, nothing to decide in between. When the field turns green, the change lands on your retina, crosses the visual cortex, gets stamped as a go, and runs down your arm to a muscle, all of it in roughly a quarter of a second. None of that is under conscious control; by the time you notice yourself clicking, the click has already happened.
This version keeps the classic shape of the lab task. The field turns red and holds for a random wait, so the flip cannot be counted out; the clock starts on the frame your screen actually paints the green and stops as your press comes down, not as it comes back up. Five rounds make the score, because one click is mostly luck: attention drifts, guesses land. A press while the field is still red, or one under 100 ms after the green, is a guess by definition; the round is discarded and replayed.
Your average lands on the curve below, next to everyone who has played here on top of a starting assumption from published norms, and the percentile is read off that one pool. The number also carries your machine: a screen and an input device add real milliseconds, so compare yourself with yourself on the same setup. For the whole journey from photon to muscle, there is a guide; the fine print of the curve is on the Method page.
Questions people ask
Most people land between 230 and 280 ms on a test like this, the crowded middle of the curve. Under 200 ms with a mouse is genuinely quick. The fabled sub-150 ms scores you see in screenshots are mostly fast hardware plus a lucky click, which is exactly why this test averages five runs.
Yes. A 60 Hz panel can sit on the green signal for up to ~17 ms before drawing it, and budget displays add processing lag on top. A 144 Hz gaming monitor with a wired mouse can read 20–30 ms faster than a laptop touchpad: same brain, different number. Compare yourself to yourself on the same setup.
One click is noisy: attention drifts, luck happens, a guess lands early. Averaging five runs shrinks that noise, and the consistency number (±) tells you how steady you were. A tight ± with a slow average means focus; a wide ± means one run was a guess.
A little, and less than the internet promises. Practice on this exact task trims a modest slice, mostly by wasting fewer starts; sleep, caffeine and exercise move the number more than drills do, and age moves it back, slowly. What fast players actually build is anticipation, acting on what is about to happen, which is a separate test on this site. What actually makes you faster sorts the evidence from the folklore.
It starts as an assumption worth 1000 runs, shaped from published norms, and every run played here adds one to it, everyone in one pool. The Method page says which norms, how the percentile is read, and how many runs this test has measured so far.