Tool
Key Response Test
A focused reaction-time benchmark for keyboard input. We paint a prompt, you press any key, we measure the gap. Repeated five times so a single outlier does not dominate.
5-trial latency test
Wait for the prompt, then press any key as fast as you can. Repeats 5 times. Press too early and that trial is restarted.
What this actually measures. Browsers cannot read hardware-level key latency from JavaScript. What you see is the time between a known paint frame and the keydown event firing in JS, which includes your browser’s render queue, the OS event loop, and the page’s handler latency. Typical results in a modern browser: 30–80 ms; gaming-quality input chains hit 15–25 ms. For true hardware measurement you need a high-speed camera or a dedicated latency rig.
How it works
Press Start. The panel waits a random 1.5–3.5 seconds — the random delay matters; without it you would anticipate the prompt and the measurement would be junk. Then it paints “NOW” and starts a high-resolution timer using performance.now(). When your keydown event lands, the timer stops.
Press too early (before the prompt) and the trial is flagged as a false start — we re-randomise the wait and continue. This stops you from beating the measurement by spam-pressing.
What the number contains. Your visual reaction time (the biggest piece for most people), plus the OS-to-browser event chain, plus the JS handler. Closing CPU-hungry tabs and using a wired keyboard reduces the non-reaction component to around 15-25 ms.
Related tools
Frequently asked
How does this differ from a pure reaction-time test?
A pure reaction-time test measures only your reflex. This test measures the full visible-prompt-to-key-event chain, which is what you actually experience while gaming or typing. Most published "reaction time" tools are doing exactly this measurement — they just do not say so honestly.
What is the average key response time?
For visual prompts, human reaction time averages 200-250 ms. Add 20-40 ms for the browser/OS chain. Most users see 230-290 ms here. Trained reaction sports (esports, fencing, sprint starts) push that toward 150-180 ms.
Why was my early press counted as a false start?
Because we randomise the delay, pressing before the prompt is a guess, not a measurement. We reset that trial and re-randomise. Without this guard, anyone could spam the keyboard and "win" with a 5 ms time.
Are these results comparable across devices?
Roughly. Your monitor refresh rate, keyboard polling rate, OS scheduler, and browser engine all affect the non-reaction portion of the measurement. To compare yourself fairly across devices, run the test on each with the same browser, no background load, and the same time of day.
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