⚡ Reaction Time Test
Test your reaction time: wait for green, then click or press Space. Five rounds give your average, median, fastest and consistency in milliseconds.
Your times appear here after the first round.
What Reaction Time Test Does
This reaction time test measures how quickly you respond to a visual signal. Click to start, wait while the box is red, and click, tap or press Space the instant it turns green. After five rounds you get your average, median, fastest and slowest times, and how consistent you were.
The clock starts on the actual frame in which the green is drawn, not when the code decides to change color, and the waiting time is drawn from a cryptographically secure random generator between 1.5 and 5 seconds, so there is no rhythm to anticipate. Pressing early is counted separately and the round is repeated.
Your result includes more than your brain: the screen’s refresh and processing time, and the delay of your mouse, keyboard or touch screen, are added to every round. Comparing results is only fair on the same device.
How to Use Reaction Time Test
- Click the box (or focus it and press Space) to start
- Wait while it is red — pressing early repeats the round
- Click, tap or press Space the moment it turns green
- Complete five rounds to get your average and median
- Compare against your saved personal best
Formula Used by Reaction Time Test
Why the median matters
Median = middle value of your sorted times; consistency = standard deviation
Worked example
Rounds of 231, 245, 219, 402 and 238 ms.
- Sorted: 219, 231, 238, 245, 402
- Average = 267 ms
- Median = 238 ms
Result: One distracted round (402 ms) pulls the average up by about 29 ms; the median barely moves.
Hardware Delay Hidden in Every Score
Upper bounds of the delay each factor can add; actual values depend on the device.
| Source | Up to |
|---|---|
| 60 Hz display refresh (one frame) | 16.7 ms |
| 120 Hz display refresh | 8.3 ms |
| 144 Hz display refresh | 6.9 ms |
| USB mouse polled at 125 Hz | 8 ms |
| USB mouse polled at 1000 Hz | 1 ms |
How to Read Your Result
What affects reaction time
Alertness is the biggest everyday factor: sleep, time of day and fatigue all shift results noticeably. Alcohol and some medications slow reactions. With practice on a specific task, times usually improve and become more consistent, and average times tend to rise slowly with age.
Simple vs. choice reactions
This is a simple reaction test — one signal, one response. Real tasks like braking in traffic involve spotting the hazard and choosing what to do, which takes considerably longer than a lab-style click. A fast score here does not mean a shorter stopping distance.
Limitations & Accuracy Notes
- Results include display and input latency, which differ between devices and can vary by tens of milliseconds.
- Browser timing is precise to about a millisecond, but background tabs, power saving and heavy system load can delay frames.
- This is a game and self-check, not a medical or fitness-for-duty assessment.
Frequently Asked Questions
How does the reaction time test work?
What is a good reaction time?
Why is my reaction time slower on this computer?
What happens if I click too early?
Can I improve my reaction time?
Is my best score saved?
References & Further Reading
- Refresh rate — Wikipedia — Frame timing at common refresh rates