Reaction Time Test

2026-10-12

Check how fast you react to a colour change or to a short beep. A run has five valid tries, and the page shows your average, median and best time in milliseconds.

How to use the reaction time test

1. Choose Colour change or Sound. In sound mode, press “Play test beep” first and set your device volume to a comfortable level.
2. Press the large area to start a try: click it, tap it, or press Space or Enter. It says “Wait...”.
3. After a random pause of roughly 1.5 to 5 seconds the area turns green and says “Now! Press” (in sound mode a short beep plays instead). React as fast as you can with the same input; your time in milliseconds appears.
4. Press again for the next try. Pressing before the signal gives “Too soon”; a reaction under 100 ms gives “Too fast”. Neither is counted, and the try is repeated.
5. After five valid tries you see every try, the average, the median and the best time. “Try again” starts a new run.

How it works

Every try draws a new random waiting time between 1.5 and 5 seconds, so there is no rhythm to learn. In colour mode the page changes the colour inside a requestAnimationFrame callback, which runs just before the browser draws a frame, and starts the timer at the beginning of the next frame, close to the moment the new colour is first drawn. A web page cannot know when pixels really light up, so that screen delay stays in your result.

Your press is read from the pointerdown or keydown event, the moment you press down, not the release. The event timestamp uses the same clock as the timer, so the reaction time is the press timestamp minus the start timestamp, rounded to a whole millisecond. Holding a key down counts once. In sound mode the beep (1,000 Hz, about 0.16 seconds, fixed moderate level) is scheduled on the audio clock about 80 ms ahead, and the start time is that scheduled moment; the delay of the audio output is not compensated.

A press during the wait cancels the pending signal. A try is also cancelled if you hide the tab or press Esc, and discarded as “No reaction” if nothing happens within 4 seconds. The average is the sum of the five times divided by five; the median is the middle of the five sorted times; both are rounded to a whole millisecond.

Examples

Example 1: steady. Tries 245, 232, 261, 228 and 254 ms. The sum is 1,220, so the average is 1,220 / 5 = 244 ms. Sorted: 228, 232, 245, 254, 261, so the median is 245 ms and the best is 228 ms.

Example 2: one slow try. Tries 310, 285, 402, 295 and 288 ms. The sum is 1,580, so the average is 316 ms. Sorted: 285, 288, 295, 310, 402, so the median is 295 ms.

Example 3: sound mode. Tries 180, 175, 190, 172 and 183 ms. The sum is 900, so the average is 180 ms. Sorted: 172, 175, 180, 183, 190, so the median is also 180 ms.

Example 4: rounding. Tries 231, 247, 238, 252 and 229 ms. The sum is 1,197, so the average is 1,197 / 5 = 239.4, shown as 239 ms. Sorted: 229, 231, 238, 247, 252, so the median is 238 ms.

What reaction time is and what the test measures

Simple reaction time is the time between a signal and the start of your response when you know what the signal will be and what to do. It adds up from several steps: the sense organ turns light or sound into nerve signals, the brain notices the signal and decides to act, a command travels to the muscles, and the finger presses. Choice reaction time, where different signals need different responses, is longer. The result here also includes the technical delays described below.

Typical values

In laboratory studies of healthy young adults, simple reaction time to a light is typically around 180 to 250 ms, and to a sound typically around 140 to 200 ms. Sound is usually faster because the hearing pathway typically needs less time to deliver the signal. Individual values vary a lot, and also from try to try in the same person.

Online tests typically read higher by tens of milliseconds, because screen, input and browser delays are added to the human part. A colour test on an ordinary computer often lands between 200 and 300 ms.

Why the number differs between devices

• Display refresh interval. A 60 Hz screen draws a new image every 16.7 ms, a 144 Hz screen every 6.9 ms, so the colour can appear up to one interval late.
• Display processing. Some screens, especially televisions with image processing, hold the picture for tens of milliseconds.
• Input device. Mice and keyboards report at a fixed rate, for example 125 times per second, which can add up to 8 ms. Touchscreens usually add more.
• Browser timing. Power saving can lower the frame rate.
• Audio output. Wired headphones add little, wireless ones often add 100 ms or more.

Compare results only from the same device, input and headphones.

Average, median and best

The average uses every try but is pulled by an odd one, such as a try where you looked away. The median is the middle try, so it is steadier. If the two are close, the run was consistent; if the average is much higher, one slow try is the reason. The best time shows what is possible on your setup, but with five tries it is the least stable number.

What affects reaction time

• Sleep and tiredness. Lack of sleep slows responses and makes them less regular.
• Attention. Distractions and rushing add slow tries.
• Age. On average, simple reaction time becomes slightly longer with increasing age, with large differences between individuals.
• Practice. The first tries are often slower; after a few runs the improvement levels off.
• Substances. Alcohol slows reactions. Caffeine can modestly improve alertness in some people, mainly when tired.

How to get a consistent measurement

• Use the same device, input and, in sound mode, the same headphones every time.
• Close other tabs and programmes, and do one practice run first.
• Compare medians of several runs, not single tries, and do not guess the signal.

Frequently asked questions

What is a good reaction time?

There is no single threshold. Typical online results for a colour change are roughly 200 to 300 ms, and sound results are often somewhat lower, but a faster or slower screen or input device changes that.

Why is my sound result different from my colour result?

The human part is typically faster for sound, but the audio output adds its own delay, small with wired headphones and large with wireless ones. The modes are not directly comparable.

Why does the page say “Too fast”?

A reaction under 100 ms is faster than people can react to an unexpected signal, so it is almost always a guess made before the signal. Such tries are not counted and are repeated.

Can I improve my reaction time?

A little. Being rested and focused and doing a few practice runs helps; large gains are unlikely.

Is this a medical or scientific test?

No. It is a simple self-test for curiosity and comparison. It cannot diagnose anything; if you are worried about your health, talk to a doctor.

Is my data sent anywhere?

No. The test runs entirely in your browser. The history of your last runs is stored in this browser on this device only, and “Clear history” removes it.

Related tools

• Typing Practice — train accuracy and speed on the keyboard.
• Typing Speed Test — measure words per minute.
• Typing Game — type falling words in time.
• Headphone Test — check left and right channels.
• Tone Generator — produce pure tones.
• Histogram Maker — plot many of your times.