Take a reaction time test online — nothing to download or install. It runs entirely in your browser using a high-resolution timer for accurate millisecond measurement, on desktop and mobile.
Click, tap, or press Space when the panel turns green.
An online reaction test is instant and free. There's no software to install and your results are saved locally so you can track progress and, if you sign in, compete on global leaderboards.
You can test on any device. Because touchscreens and mice have different input latency, compare results within the same device rather than across devices.
Yes — the test is touch-friendly and fills most of the screen so it works well in both portrait and landscape.
No. You can take the test anonymously. An account lets you save history, earn achievements and join leaderboards.
It uses the browser's high-resolution clock, but hardware and display latency add a small offset. Read our methodology for the full picture.
ReactionLab is a browser-based reaction performance test. It is not a medical, neurological, or intelligence assessment. Results depend on your hardware, input device, and browser. See our methodology.