Reaction Time Test

Understand your five rounds

Average time and best time answer different questions

Lower times mean a quicker recorded response. The average adds the five valid round times and divides by five; the best time is the lowest single value. Each round and the displayed average are rounded to whole milliseconds.

For example, rounds of 240, 260, 250, 310, and 240 milliseconds add up to 1,300. Your average is 260 ms and yourbest is 240 ms. The 310 ms round raises the average, which is useful information about consistency rather than a reason to discard it.

An early press is excluded and restarts the same round. It is not counted as a fast score or added as a penalty to the average. Repeated guessing can still distort a session, so wait for GO rather than trying to predict it.

What a browser can actually measure

The clock starts when the page switches to its ready state, just before drawing the GO signal, and stops when the input event is handled. It cannot directly observe the instant light reaches your eyes or separate your response from display, operating-system, and input-device delays.

At 60 Hz, a display refresh interval is about 16.7 milliseconds; at 120 Hz, it is about 8.3 milliseconds. That does not tell you how much to subtract from a score: the page may become ready anywhere within an interval, and other delays are also present. Millisecond units do not mean millisecond accuracy.

Keep the test tab visible throughout a session. Browser work, a background tab, or a device going to sleep can delay the signal or its handling. If the session is interrupted, restart it and record that the conditions changed.

Make a comparison you can use

Use the same device, browser, input method, and test position for each comparison. Do a practice session to learn the controls, then record the average and all five rounds from two or three sessions. Include a short note about interruptions or changes in setup.

If one session averages 260 ms and the next 254 ms, that six-millisecond difference alone is not evidence of a lasting change. Look for a repeated pattern under similar conditions. Mouse, touch, and keyboard results should be kept separate because their input paths differ.

This tool has no calibrated reference population, age-based rankings, or diagnostic threshold. It cannot assess fitness to drive or identify a health condition. Treat the numbers as results from this particular browser task. The Typing Speed Test measures a different task: entering a passage accurately over time.