Free Reaction Time Test
Measure your visual reaction time in milliseconds over five attempts, with false-start detection, average, median and best, plus saved history.
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How to measure your reaction time in milliseconds
This is the classic simple visual reaction test. A random delay stops you from predicting the signal, and presses that come too early are caught as false starts. Use it to track your own reflexes over time, compare devices or warm up before a game. For raw clicking speed rather than reaction, use the Click Speed Test.
- Click the blue box to begin. It turns red: keep your finger ready but do not press.
- After a random wait of 1.5 to 5 seconds the box turns green. Click, tap or press Space or Enter immediately.
- Your time appears in milliseconds. Click again to start the next attempt.
- If you press while the box is red, or within 100 ms of green, it counts as a false start and that attempt is repeated.
- After five valid attempts, read your average, median, best and spread, and find the series in your saved history.
What a reaction time test measures
This test measures simple visual reaction time: how long it takes from a screen changing colour to your finger pressing a button. It is the same idea used in many classic psychology experiments, and it is a fun benchmark for gamers, drivers, athletes and anyone curious about their reflexes.
Because a single attempt can be affected by a blink or a lapse of attention, the tool groups five valid attempts into a series and shows the average, median, best and slowest time. Saved history lets you compare morning and evening, rested and tired, or one mouse with another. If you want to measure how many clicks you can make rather than how quickly you respond, use the Click Speed Test.
Worked example: one five-attempt series
Suppose your five valid attempts are 312, 287, 341, 295 and 268 ms. The average is the sum, 1,503 ms, divided by 5, which is 300.6 ms. Sorting the times gives 268, 287, 295, 312, 341, so the median, the middle value, is 295 ms. The best is 268 ms, the slowest 341 ms, and the spread (standard deviation) is about 24.7 ms.
If you had pressed once while the box was still red, the tool would have recorded a false start and asked you to repeat that attempt; the series still needs five valid times, and the false start count is saved with it. Now consider the screen: at 60 Hz a new frame is drawn every 16.7 ms, so on average the green appears about 8.3 ms after it was triggered. At 144 Hz the frame interval is 6.9 ms and the average wait about 3.5 ms.
How the timing works
After you start an attempt, the box turns red and the page picks a random delay between 1.5 and 5 seconds, so you cannot predict the signal. When the delay ends the box turns green, and the page records the timestamp of the animation frame that draws it. Your press is timed with the event’s own high-resolution timestamp, which is taken when the browser receives the input rather than when the page gets round to handling it.
A press before green is a false start. A press under 100 ms after green is also treated as a guess rather than a reaction. Only valid times count toward the series. Your finished series, with its date, average, median, best and false starts, is stored in local storage on this device; the 50 most recent series are kept.
Why your score includes hardware delay
No web page can measure pure human reaction time. The number includes the wait for the next display frame, the monitor’s own processing and pixel response time, and input delay from the mouse, touchscreen or keyboard, its USB or wireless connection and the operating system. Together these commonly add tens of milliseconds, and they differ between devices.
That is why results are best compared on the same setup. Wireless mice in power-saving mode, televisions without a game mode, Bluetooth keyboards and busy computers all add delay. Touchscreens often add more than a wired mouse. A lower number on a new monitor may reflect better hardware rather than faster reflexes.
Useful tips and limitations
- The median is often the fairest single number because one slow, distracted attempt does not pull it up as much as it does the average.
- Test on the same device and input each time. A wired mouse and a high refresh rate screen lower the measured time.
- Look at the centre of the box and rest your finger lightly on the button; moving your eyes or finger toward the target costs time.
- Run two or three series and keep the best median rather than relying on a single lucky attempt.
Common questions
What is a normal reaction time?
Simple visual reaction times for alert adults are commonly in the region of 200 to 300 ms when measured on a computer, and online tests include extra display and input delay. Compare your own results over time rather than against a single fixed number.
Why is my time slower on one device than another?
Screens differ in refresh rate and processing delay, and mice, touchscreens and keyboards differ in input lag. A 60 Hz display only draws a new frame every 16.7 ms, while a 144 Hz display draws one every 6.9 ms.
Why did my very fast press count as a false start?
Presses within 100 ms of the green signal are treated as guesses, because that is faster than a genuine visual reaction. Sprint starting systems use the same 100 ms limit.
Can I use the keyboard instead of a mouse?
Yes. Focus the test area and press Space or Enter. Held keys do not repeat, so each attempt needs a fresh press.
Does the test work on phones and tablets?
Yes. Tap the box. Touchscreens can add more input delay than a mouse, so compare phone results with other phone results.
Is my history shared or uploaded?
No. It is stored only in this browser on this device and you can clear it at any time.
Everything runs in your browser. Scores and history are saved only in this browser’s local storage on this device, and you can delete them at any time with the reset button.