Reaction time test
Tap as soon as the panel turns green. Five tries give you an average in milliseconds, and the calculator below shows how that same delay creeps into every hand-timed stopwatch result.
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What counts as a good reaction time?
Simple visual reaction time for alert adults is usually quoted at around 200–250 ms in lab conditions. Online tests like this one read a little slower because your screen, touch panel or mouse add their own delay: a 60 Hz display can show the green up to 16.7 ms late, and touchscreens and wireless mice add more. Compare your scores on the same device rather than against someone else's phone.
Sprinters react to the gun in roughly 0.12–0.18 s. World Athletics treats any reaction under 0.100 s, measured by sensors in the starting blocks, as a false start, on the basis that nobody can genuinely respond to the sound faster than that.
Why this matters for stopwatch timing
Every press of a stopwatch button includes a reaction like the one you just measured. That is why hand-timed sprint results are published only to a tenth of a second, and why official records require fully automatic timing. Timekeepers watching for the smoke of the gun start late, while at the finish they can anticipate a runner they see approaching, so the two errors don't cancel and hand times tend to come out quicker than electronic ones. Our accuracy guide goes further.
How to get a fair score
- Use a wired mouse or tap directly on the screen; avoid Bluetooth peripherals.
- Rest your finger on the button. Don't guess: early taps are rejected and the delay before green is random.
- Close other heavy tabs so the page can redraw on time.
Questions people ask
What is the average human reaction time?
For a simple visual signal, typical adult values are around 200–250 ms in controlled tests. Online, with display and input lag included, most people score about 200–300 ms.
How is my reaction time measured here?
The page records a high-resolution timestamp when the panel turns green and another when your tap or key press arrives, then shows the difference. The wait before green is random between 1.5 and 4.5 seconds.
Why is my score slower on my phone?
Touchscreens scan for input at a limited rate and screens refresh 60–120 times per second, which can add tens of milliseconds. Compare scores on the same device.
Can I improve my reaction time?
Sleep, alertness and practice with the specific task help a little; caffeine can too. Most gains on a simple test like this come from focus and consistent technique.