Method / Updated November 7, 2026

How the test works

The score is the time between the moment your browser is asked to show the signal and the moment it timestamps your click, tap or key press. It includes your reaction and your setup.

What we measure

1. After you start, the test waits for 1.5 to 4.5 seconds so you cannot time the signal.
2. At the next animation frame, the page changes to the bright signal and records the time. This is when the change was committed in the browser. It is not the moment your display lit up.
3. Your input carries its own browser timestamp. Your attempt time is the input timestamp minus the commit time.

We do not add or subtract any fixed correction for frame length or hardware.

Which attempts count

The test ends after five valid attempts. An attempt does not count when:

• You respond before the signal.
• You respond in under 100 ms. This is below the range this test accepts, and it may mean you responded early.
• You take more than 2,000 ms.
• You leave the page or tab, or the browser cancels your input.
• The browser gives a timestamp we cannot trust.

The 100 and 2,000 ms limits are our product rules, not scientific verdicts about you. The test pauses after three counted invalid attempts without a valid one, so you can reset. Attempts interrupted by leaving the page do not add to this count.

How your score is calculated

• Median: the middle of your five valid attempts. One unusual attempt affects it less than an average.
• Best: your fastest valid attempt.
• Consistency: the interquartile range of your valid attempts. Lower is steadier.
• Attempts used: valid and invalid attempts together.
• Tier: a plain guide we chose. It is not a percentile or a ranking.

What this test cannot do

• It cannot separate your reaction from your mouse, touchscreen, keyboard, display, system or browser.
• It has not been calibrated with physical measurement equipment, so we make no claim about its accuracy in milliseconds.
• Browser pace is an estimate of how often the browser draws frames. It does not prove your display's refresh rate.
• Scores from different devices are not directly comparable. Compare on the same setup.
• It is not a medical or diagnostic test.

How the friend challenge works

A challenge link holds a seed and the sender's median in the part of the address after the #. Browsers do not send that part when requesting the page. Your friend gets the same starting wait sequence. An invalid attempt changes the wait for that retry, so two runs may not match exactly.

The score comes from the link and is not verified. There is no account, name or public leaderboard.