About reaction time
Human visual reaction time to a simple stimulus like a color change is typically around 200 to 300 milliseconds, with some variation from tiredness, practice and attention. This test measures the time between the box turning green and your click, using the browser's high-resolution timer.
Clicking during the red waiting phase counts as a false start and is not scored, since anticipating rather than reacting is not a genuine measurement. Your best time and recent average are tracked locally in your browser only.
How is reaction time measured and what's a good score?
Reaction time is measured as the time between a stimulus (the box turning green) and your response (your click), recorded in milliseconds using the browser's high-resolution timer. Human visual reaction time to a simple stimulus is generally reported to be in the 200-300 millisecond range, though individual results vary widely.
Steps to take the reaction time test
- Click the box to start a new attempt.
- Wait while the box stays red or another idle color — clicking now counts as a false start.
- As soon as the box turns green, click it as fast as you can.
- Your time in milliseconds appears immediately, along with your rolling average over the last 5 attempts.
- Click reset to clear the average and attempt count, though your all-time best is kept separately.
How the timer works
Reaction time (ms) = timestamp at your click - timestamp when the box turned green
- High-resolution timer = a browser API that measures elapsed time with sub-millisecond precision
- False start = clicking before the box turns green, which is not scored since it reflects guessing rather than reacting
General reference ranges
| Range | General description |
|---|
| Under 200 ms | Very fast — reported for elite esports players and sprinters in some studies |
| 200-300 ms | Commonly reported as typical for simple visual reaction |
| 300-400 ms | Reported as slower than average, possibly due to fatigue or distraction |
| Over 400 ms | Reported as notably slow for simple reaction, worth retesting rested |
Frequently asked questions
Why doesn't clicking during the red phase count?
A click before the box turns green is a guess, not a reaction to anything — since there's no stimulus yet, timing it would not measure your actual reaction speed. The tool flags this as a false start and asks you to try again instead of recording a number.
Why is there a random delay before the box turns green?
If the delay were fixed, you could learn its timing and anticipate the color change instead of genuinely reacting to it, which would produce artificially fast but meaningless results. Randomizing the wait time forces each attempt to measure real stimulus-response speed.
Why does my reaction time vary so much between attempts?
Reaction time naturally fluctuates due to attention, fatigue, practice effects, and even the device or display you're using, so a single result is less meaningful than your average over several attempts, which smooths out random variation.
Are my results sent anywhere or shared?
No. Your best time and recent average are stored only in your browser's local storage and are never transmitted to a server or shared elsewhere.
This test measures simple visual-motor reaction time in a browser, which is affected by device input lag, display refresh rate, and browser performance; treat results as a rough personal benchmark for tracking your own trend over time, not a precise scientific measurement.
Privacy and safety
- Runs in your browser — Everything you type is calculated on your own device. Your inputs are never sent to a utilduck server.
- Encrypted connection — Pages are served over HTTPS, so nobody on the network can read what you load.
- Not shared with third parties — Your inputs are not passed to analytics or advertising services.
- Nothing is stored — Results are not saved to any server, and there is no account to create.
Last updated: 2026-08-17