Reaction Time Test — Measure Your Reflexes in Milliseconds

Wait for green. Tap. See your milliseconds.

Reflex
2 min
Easy

Wait for the screen to turn green, then tap or press a key. HumanCalc averages five rounds and shows your reaction time in milliseconds. Keep the same device and input method when comparing attempts, because browser, display and input delays affect the result.

Play Reaction Time

How it works

1Wait on red. The delay is unpredictable on purpose.

2It turns green. Tap immediately.

3Several rounds, averaged. That average is your score.

How to play

1
Wait for the signal
The screen waits for an unpredictable interval. Keep your finger ready and wait for green.
2
Tap on green
When it turns green, tap or press a key. An early tap receives a 1,500ms penalty in the session average.
3
Repeat, then average
Several rounds are averaged. The average is your score — outliers matter.

What it trains

Cut the delay between seeing and acting. Simple reaction time isolates the delay between a sensory signal and a motor response, with no decision step in between.

Practice focus: Reflex
Based on: Donders, 1969 translation of the original work

Research background

Donders: On the speed of mental processes

These sources describe related tasks or concepts. HumanCalc adapts them for browser practice; a game score is not a clinical result.

Leaderboard

Weekly season resets every Monday. Scores show as 250ms.

Leaderboard

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Questions

What is a good reaction time?

Compare repeated five-round averages on the same device. HumanCalc has no verified population percentile, and a single low result can reflect anticipation rather than a consistent response.

Why is my phone slower than my laptop?

Touchscreens, keyboards, mice, display refresh and browser scheduling introduce different delays. HumanCalc does not measure or subtract those delays, so compare results using the same setup.

Can reaction time be trained?

You can practise this task and observe your consistency. A change in a browser score does not by itself identify a change in your underlying nervous system or performance in another activity.