Take the reaction time test online
There is nothing to install. Press Start test and the panel turns red. After a random wait of about 1.5 to 5 seconds it turns green, and you click, tap or press Space. Five tries are averaged into one score in milliseconds. A click before green cancels that try and it is repeated.
Your results are saved in this browser and listed in the Your scores panel.
What an online test can measure
An online test is good at relative questions, the kind where you compare one of your own runs with another.
- Whether you are faster or slower than you were last week.
- Whether a bad night’s sleep shows up in your average.
- Whether a new mouse or monitor changed your result.
- How you compare with a friend who uses the same device.
In each case the delay from your equipment stays the same, so it cancels out.
What it cannot measure
It cannot give you an exact, lab-grade figure. The browser can time events very precisely, but it cannot see the delay between drawing the green panel and the light leaving your screen, or between your finger moving and the click arriving. A 60 Hz screen refreshes every 16.7 ms and a 144 Hz screen every 6.9 ms, and input devices add more on top.
That is why online results sit at 250 to 300 ms while lab studies of young adults report about 200 to 250 ms. It is also a general interest tool. It does not diagnose anything.
Browser and device effects
| Setup | What to expect |
|---|---|
| Desktop, monitor and wired mouse | Usually the least added delay |
| High refresh rate monitor | The green panel appears sooner |
| Phone or tablet | Touch input adds its own delay |
| TV used as a screen | Image processing can add tens of milliseconds |
| Many heavy tabs open | Frames can be delayed |
Whatever you use, keep to the same browser and device each time and close what you do not need.
Getting a result you can trust
Take the test three times on one device and read the average, not the best try. The reaction time tester page goes deeper into how the timing works, and the human reaction time test page shows where your score sits against typical results.