Reaction Time Test — how fast are your reflexes?

A reaction time test measures how long it takes you to respond to a sudden signal. In this visual version, a panel turns from red to green after a random delay; the timer starts the instant it is green and stops when you click, tap, or press a key. The result, in milliseconds, is your simple visual reaction time — the eye-to-brain-to-finger loop with no decision to make.

Click, tap, or press Space to start. Wait while the panel is red. The moment it turns green, respond as fast as you can. Do that five times and the test shows your average, which is the number most people mean by "my reaction time", along with your fastest single attempt. If you respond while the panel is still red it is a false start, and that attempt restarts with nothing recorded.

Yes. reactiontimetest.lol is completely free and runs entirely in your browser. There is no sign-up, no download, no app to install, and no ads interrupting a round. Open the page and the panel is ready.

No. The test is the web page. Your best time, attempt count, and history are saved locally in your browser, so there is nothing to log into. You can add the page to your home screen if your browser supports it, but you still play in the browser.

For a simple visual reaction test on a computer, roughly 200–250 ms is above average, 250–300 ms is around the norm, and under 200 ms is excellent — the range competitive gamers and athletes tend to hit. Consistently under about 150 ms is rare and usually means you are anticipating the green rather than reacting to it.

Large public datasets for this style of test cluster around a median of 270–290 ms, with about 273 ms the most frequently cited figure. Averages drift upward with age and vary with sleep, caffeine, time of day, and hardware, so treat any single number as a broad reference rather than a fixed target.

A single attempt is noisy — it can land 80–100 ms away from your true speed just from natural variation and the odd twitchy or late click. Averaging five clean attempts smooths that out and gives a number you can actually compare from one day to the next. Your best single attempt is shown too, but the average is the more meaningful score.

The practical floor for reacting to a visual signal is around 100–120 ms, set by how long the signal takes to travel from your retina through your brain to your hand. Anything much below that on this test is a lucky early click, not a genuine reaction.

The software side is accurate: it uses a high-resolution timer and re-stamps the green moment to the actual screen paint, so it does not count rendering lag. The limiting factors are your hardware and your attention. A 60 Hz monitor adds up to ~17 ms of display latency, a wireless mouse adds more, and a distracted attempt adds more still. For comparable numbers, keep the device, browser, and conditions the same each time.

The panel can only turn green on a screen refresh, so a faster refresh rate shows you the signal sooner — about 17 ms between frames at 60 Hz versus about 7 ms at 144 Hz. Then your input device has to report the click: a wired mouse or a direct screen tap is near-instant, while Bluetooth mice and some trackpads buffer input and quietly add tens of milliseconds to every attempt.

Cold reaction time is genuinely slower — the visual-motor loop needs a moment to warm up. The first one or two attempts of a session are almost always the slowest. Take a few throwaway attempts before you start a round you care about.

Yes. The layout stacks so the panel and instructions sit above the fold with nothing to scroll past, and you tap straight on the panel. Direct touch is usually lower latency than an external pointer, though phone displays vary in how quickly they show the colour change.

Somewhat. Most people can trim 10–40 ms through setup and warm-up alone, and a bit more with consistent sleep, aerobic exercise, hydration, and practice at fast-paced tasks like ball sports, rhythm games, or action games. The gains are real but bounded — you are not going to halve a 250 ms reaction — and they show up as a trend over weeks, not in a single session.

Moderate caffeine does modestly speed up simple reaction time for most people, on the order of 10–20 ms, and can help offset fatigue. Too much can add jitter and false starts, and the effect fades as tolerance builds. Sleep is the larger and more reliable lever.

A false start means you responded before the panel turned green — almost always because you were trying to predict the timing. The delay is randomised on every attempt specifically so it cannot be timed. Wait for the colour to actually change; reacting a few milliseconds later beats restarting the attempt.