Reaction Time Test

This reaction time test measures how quickly you respond to a signal. Wait for the red screen to turn green, then click, tap or press Space as fast as you can. After five trials you get your average, your best and your spread in milliseconds. It is free, runs in your browser with no download or sign-up, and works with a mouse, a keyboard or a phone’s touch screen.

What the test measures

Your reaction time is the gap between the moment the signal appears and the moment your press is registered. The test offers three modes:

• Simple: the classic version. The screen turns from red to green, and you press anywhere on it.
• Choice: the left side lights up blue or the right side lights up orange, and you press that side. Use the Left arrow or A and the Right arrow or D, or tap the lit half on a touch screen.
• Audio: the screen stays the same and a short beep plays instead. Press as soon as you hear it. Turn your sound on first.

How to use it

• Click, tap or press Space to start. The screen waits a random 1.5 to 5 seconds, so you can’t learn the rhythm.
• Press the moment the signal appears. Your time for that trial is shown in milliseconds, and you tap again for the next one.
• If you press before the signal, you see Too soon. That trial doesn’t count and is run again. In choice mode, pressing the wrong side also restarts the trial.
• After five counted trials, the results screen shows your average, best, slowest and spread. Tap or press Space to try again.
• Press P or Esc to pause. Switching tabs pauses too. A paused trial is restarted with a new random wait, so it can’t give you a false time.

The test counts the moment your finger or key goes down, not when you let go, and times everything with your browser’s high-resolution clock.

How to read your result

The big number is your average across the five trials. Best is your fastest single trial and slowest is your slowest. Spread is the standard deviation, which shows how much your trials varied. A small spread means you were consistent. A large one usually means one or two trials were slow. When your times vary a lot, the results screen also gives your median.

For reference, Wikipedia’s article on mental chronometry gives a mean reaction time for college-age people of about 190 milliseconds to detect a visual stimulus and about 160 milliseconds to detect a sound. Expect your numbers here to run higher. Your mouse or keyboard, your touch screen, your display’s refresh and processing, and your speakers or headphones all add delay before the browser sees your press. Wireless headphones can add a lot in audio mode. Compare results on the same device for a fair picture.

This is a test for fun and practice. It is not a medical or diagnostic test.

Each finished set is saved in your browser, separately for each mode. The history chart plots your last 20 averages and highlights your best in yellow. Clear history asks for a second click and only clears the mode you are viewing.

Tips for a faster time

• Don’t guess. The wait is random, so anticipating usually earns a Too soon. Watch the screen and react.
• Rest your finger on the button. Keep a finger lightly on the mouse button or Space bar so there is no distance to travel.
• Use a wired setup. A wired mouse or keyboard and a high refresh rate display reduce the delay your device adds.
• Do a few sets. Warm up, then use the history chart to see how you settle in.

FAQ

Is the reaction time test free?

Yes. It’s free with no account and nothing to install. One click or tap starts the first trial.

Why is my time slower on my phone?

Touch screens and phone displays often add more delay than a wired mouse and a fast monitor. Compare phone results with phone results.

What does Too soon mean?

You pressed while the screen was still red (or before the beep in audio mode). That trial is thrown out and run again with a new random wait.

Why does choice mode give slower times?

In the simple test you know which button to press before the signal appears. In choice mode you first have to see which side lit up and then pick a response, and that decision takes extra time.

Want more quick brain tests? Try the Chimp Test to check your working memory, or put your reflexes to work in Whack a Mole.