Reaction Time Test: How Fast Are You?
After a random delay the area turns green – then tap, click or press the space bar. After five tries you get your average, median and best time; your history stays saved in this browser.
How it is calculated
How the reaction time test works
This test measures your simple reaction time: the time between a signal and your response to it. There is only one signal (the area turns green) and one response (tap, click or press a key).
- Start: tap the area or press the space bar. It turns red and shows “Wait …”.
- Wait: after a random delay between 2 and 5 seconds it turns green. The delay changes every time, so you can’t guess the moment.
- React: as soon as “Now!” appears, tap as fast as you can. Your time in milliseconds (ms) appears on the area.
- Five tries: afterwards the test shows your average, median and best try.
False start
If you press before the area is green, it counts as a false start. That try isn’t scored and is simply repeated; the number of false starts is shown below the area. Switching tabs during a try cancels it without scoring.
Average, median and best
- Average: the sum of all five times divided by five.
- Median: the middle value of the five sorted times. One sleepy try barely moves it – which often makes it the fairer number to compare.
- Best try: your fastest single time. Across all tests the page also remembers your personal best and your best average.
What exactly is measured
The timer starts when the page switches the area to green and stops when your input reaches the browser. It uses performance.now(), a clock with sub-millisecond resolution. With mouse and touch the test reacts to the press (pointerdown), not to the release.
Important: every result also includes your device’s delay – how quickly the screen shows the green and how quickly mouse, keyboard or touchscreen report your input. That’s why we deliberately don’t quote a general “normal” value here: compare your results with your own, on the same device.
Tips for comparable results
- Always use the same device and the same input (e.g. only space bar or only mouse).
- Don’t guess: a false start costs time and isn’t scored.
- Do several tests and look at the median – single outliers are normal.
Privacy
Best times and history (up to 50 tests) are stored only in your browser’s localStorage and never sent to a server. “Clear history” removes them. The random delay comes from the browser’s cryptography interface.
More games: Tic-tac-toe, Sudoku or the dice roller.
Frequently asked questions
How does the reaction time test work?
Tap the area, wait until it turns green, then tap as fast as you can. The time in between is measured in milliseconds. After five valid tries you see your average, median and best time.
Can I take the reaction time test with the space bar?
Yes. Space or Enter start a try and stop the timer once the area is green. Holding a key down doesn’t count more than once.
Does the reaction time test work on mobile?
Yes. On phones and tablets simply tap the area; the test reacts as soon as your finger touches the screen. Keep in mind that the touchscreen’s own delay is included in the result.
What is a good reaction time in ms?
We deliberately don’t give a general benchmark: every result includes the delay of your screen and input devices, which differs from device to device. The meaningful comparison is with your own results on the same device.
Why are my results different on my phone and my PC?
Touchscreens, displays and browsers report input and show colors with different delays. This device latency is part of every measurement, so only compare results from the same device.
What is the difference between average and median?
The average is the sum of the five times divided by five. The median is the middle value of the sorted times. A single slow try changes the average a lot but the median hardly at all.
What happens on a false start?
If you press before the area turns green, the try isn’t scored. Just repeat it with the next tap; false starts are counted and shown.
Sources and legal basis
- Wikipedia: Mental chronometry
- Wikipedia: Median
- MDN: Performance.now()
- MDN: pointerdown event
- MDN: Crypto.getRandomValues()
As of:
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