Reaction time test: 5 trials with mean and median

Click as soon as the screen turns green: 5 trials timed to the millisecond, false starts detected, then your mean, median and benchmark from a published study.

How the test measures your reaction time

Simple reaction time is the delay between a visual signal appearing and your press. Across 1,469 adults aged 18 to 65, Woods et al. (2015) measured 231 ms on average, or 213 ms once hardware delays were removed.

The measurement

After a random delay of 1.5 to 4.5 seconds, the area turns green. The tool records the moment of the frame that shows green with performance.now(), then the moment of your press (pointerdown event, or the Space or Enter key). Your reaction time is the difference. A press before the green is a false start: the trial does not count and is repeated.

Example series

Five trials at 245, 212, 298, 231 and 226 ms give a mean of (245 + 212 + 298 + 231 + 226) ÷ 5 = 242.4 ms. Sorted, they read 212, 226, 231, 245 and 298 ms, so the median, the middle value, is 231 ms. The median copes better than the mean with a missed trial such as the 298 ms one.

What the result includes

  • Display latency: at 60 Hz one frame lasts 1,000 ÷ 60 ≈ 16.7 ms, and the screen adds its own processing time.
  • The latency of the mouse, touchpad or touchscreen, then of the browser.
  • In the Woods study, the display and mouse added 17.8 ms on average. On another device the delay can be larger, so your result is indicative and is best compared with itself on the same device.
  • The study used 120 trials per person; 5 trials give an order of magnitude, not a lab measurement.

This test describes a performance at one moment. It does not replace a doctor's advice.

Sources and dates: Woods et al., Factors influencing the latency of simple reaction time, Frontiers in Human Neuroscience, 2015 (checked on 29/10/2026)

Frequently Asked Questions

What is the average reaction time of an adult?

In the study by Woods et al. (2015) of 1,469 adults aged 18 to 65, the mean was 231 ms, or 213 ms after correcting for display and mouse delays. A result close to 230 ms on this test is therefore near that average, on comparable hardware.

Why is my result slower on a phone?

The touchscreen, the display and the browser each add a delay the test cannot remove. At 60 Hz a single frame already lasts 16.7 ms; at 120 Hz, 8.3 ms. Compare your results on the same device.

Does reaction time increase with age?

Yes, slightly: Woods et al. measured a rise of 0.55 ms per year between 18 and 65. Between 20 and 60, that adds up to about 22 ms.

What happens if I click before the green?

It is a false start: the trial is cancelled and does not count towards the mean. The delay before the green is random, between 1.5 and 4.5 seconds, so it cannot be guessed.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.