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Reaction Time Test

Tap the moment the box turns green. Five taps, timed to the instant you press.

Runs entirely in your browser. Nothing you enter is uploaded or stored.

Space or Enter works too. Timed on the press, not the release.

Checking your display…

Also try:Sleep Calculator

How to use the Reaction Time Test

  1. 1Click, tap or press Space on the box to start. It turns red.
  2. 2Wait for green, then press as fast as you can. A press on red, under 100 ms, with the tab hidden or with no press for 5 seconds doesn't count, and that trial is redone.
  3. 3After 5 taps you get your median (half your taps were faster, half slower), your best and slowest tap, and how you compare with other people.
  4. 4Press Go again to beat your best, 5 more for a sharper score, or Challenge a friend to send them your score to beat.

How the test works

The box turns red, waits, then turns green. The wait is a random 1.5 to 4 seconds, so you can’t learn the rhythm and press in time with it; you have to see the green. Your reaction time is how long it takes from the green appearing to your press.

The clock starts on the exact screen frame that shows the green and stops on the press itself: the moment a mouse button or key goes down, or a finger touches the screen. That’s the same moment whichever you use, so a slow release or a phone’s delayed click never adds to your time.

A round is 5 counted taps. Anything that isn’t a fair reaction is redone instead of counted: a press on red, a time under 100 ms, a trial where you left the tab, and a green that gets no press for 5 seconds.

Why the median

After 5 taps the big number is your median: put the taps in order and take the middle one. Half your taps were faster and half slower. A single slow tap barely moves it, which is why it’s a fairer score than the average for a short test. Your best tap, slowest tap and how much your taps varied are shown beside it.

Want a steadier score? Press 5 more, sharper after a round. Every extra 5 taps go into the same median, up to 20.

What affects your reaction time

  • Sleep. Being tired is one of the surest ways to slow down. If your scores dip, look at how much you slept; the sleep calculator helps you time a full night.
  • Attention. Glancing away, or expecting the green too early, costs more than any amount of practice gains.
  • Warming up. Your first few taps are often slower than the rest. That’s another reason the median is the headline.
  • Your device. The screen, mouse and keyboard all add delay before you even see or send anything; see below.

Your device’s delay

Nothing on a screen appears instantly: the picture changes a set number of times a second, and the green waits for the next change. The tool measures your display’s rate and shows it under the box.

Display New picture every The green can be up to
60 Hz 17 ms 17 ms late
120 Hz 8 ms 8 ms late
144 Hz 7 ms 7 ms late
240 Hz 4 ms 4 ms late

Your input device and the screen’s own processing add more. So the fairest comparison is with yourself, on the same device: the tool keeps your best and today’s goes in this browser so you can see whether you’re getting faster.

Questions

What is a good reaction time?
Most people react to a colour change in about 200 to 300 ms on an online test, including the delay their screen and mouse add. On a large online reaction test the typical (median) time is 273 ms and the average 284 ms, so under 250 ms is faster than most people and 200 ms is faster than nearly 9 in 10.
Why is my score the median and not the average?
One slow tap, from a sneeze or a glance away, drags an average a long way but barely moves a median. Taps of 252, 251, 1,502, 254 and 254 ms average 503 ms, which says nothing true about your reflexes; their median is 254 ms. Your average is still shown, with every tap, under your score.
Why didn't a tap count?
Four things void a trial, and each is redone rather than counted: pressing while the box is red (too soon), a time under 100 ms (too fast to be a reaction to the green, so it was a guess), leaving the tab during a trial (the browser pauses timers, so the time can't be trusted), and no press within 5 seconds of the green.
Why does it time the press and not the release?
Your reaction is the moment you press. Some tests stop the clock when you let go of the button, which adds however long you held it down. This one stops it the instant the button goes down, the instant a key is pressed, and on a touch screen the instant your finger lands.
Does my screen affect my score?
Yes. A screen shows a new picture a set number of times a second: on a 60 Hz screen that's every 17 ms, so the green can appear up to 17 ms after it's due. Your mouse or keyboard and the screen's own processing add more; around 30 ms is typical for a computer. The tool measures your display's rate and shows it under the box, so compare scores made on the same device.
Is my score worse on a phone?
Often a little. Touch screens take longer to report a touch than a mouse takes to report a click. This test counts from the moment your finger lands, not from the click a phone sends afterwards, which comes later still. Compare phone scores with phone scores.
How is "faster than X% of people" worked out?
From the published results of a large online reaction test: a typical (median) time of 273 ms and an average of 284 ms. Reaction times bunch up with a long tail of slow ones, so the tool fits the standard curve for that shape (a log-normal) to those two numbers and reads your median off it. A 273 ms score is faster than 50% of people. It's an estimate, and those results come from every kind of device.
How does Challenge a friend work?
It shares a link with your score after the # (for example …/reaction-time-test#beat=246). Your friend's page reads the number and shows it as the score to beat; at the end it says who won and by how much, and they can send their own score back. Only the number is in the link, and browsers never send the part after # to a server.
Is anything uploaded or saved?
Nothing is uploaded and there's no sign-up. The test runs on this page. Your scores are kept in this browser on this device only, so it can show your best and today's goes; Forget clears them.