When the panel turns green, respond by clicking, tapping, or pressing Space. Measure your average and fastest over 5 rounds.
While it is red, keep waiting — respond only after it turns green. Pressing while it is red counts as a false start (that round is redone) and is not recorded.
🔒 Your actions and records are processed on your device — never sent to a server
Your best record (your lowest average) is stored only in this browser on this device. It is not shared with other devices.
🔒 Everything runs on your device — nothing is sent or saved to a server.
If you press while it is still red, it shows "Too soon!" and that round is redone (it is not counted). Stay calm and respond only once it turns green.
The reaction time shown includes your monitor's display latency (the time until the panel actually turns green) and the input latency of your mouse, touchscreen, or keyboard. These can vary by tens of milliseconds from one setup to another, so this number is not meant for measuring your reflexes precisely or comparing yourself with other people or devices. It works best when you measure on the same device and browser over different days and watch your own record change.
Using a high-refresh-rate monitor or a mouse and keyboard built for responsiveness tends to reduce the wait and the input delay, which can make the numbers look better. Conversely, wireless connections, power-saving settings, or a busy browser can make them larger. As part of a device check, it is interesting to see how the numbers shift with different hardware.
This tool does not judge your "brain age" or ability. The short comment based on your average is just for fun. Rather than reading too much into the number, enjoy it: take turns with family or friends on the same device, or aim to beat your own best record.
Human reaction time to a visual cue such as light or color is often cited as roughly 200–300 milliseconds (0.2–0.3 seconds). It varies with the measurement method, your setup, and how you feel, and sources disagree, so treat the number here as a rough guide for "right now, on this device". Reaction to sound tends to be faster than to sight, so the type of cue matters too.
The number shown includes your monitor's display latency (the time until the panel actually turns green) plus the input latency of your mouse, touchscreen, or keyboard. These can shift by tens of milliseconds depending on your setup, so this value is not meant for measuring your reflexes precisely or comparing yourself with other people or other devices. It works best when you repeat it on the same device and browser and try to beat your own record.
Being rested, focused, and warmed up tends to help, and simply practicing this kind of test can make you faster at it. That said, this tool is for fun, not a training program or a measure of ability. Rather than chasing a single number, try measuring on different days in the same setup and watching your own record change over time.
It can. A high-refresh-rate monitor (120Hz, 144Hz, and so on) tends to switch to green with less delay, and a gaming mouse or keyboard built for responsiveness tends to add less input latency. Conversely, power-saving settings, wireless connections, or a busy browser can push the numbers up. Seeing how your hardware affects the result is part of the fun of this test.
No. Everything runs inside your browser, and nothing you do — including your best record — is ever sent to a server. Your best record is stored only in this browser on this device (localStorage) and you can delete it any time with the "Clear record" button. It works on both computers and phones with a click, tap, or the Space key.
Prefer the Japanese version? 反応速度テスト（日本語版）
