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Start lights reaction test

Five red lights come on, then go out after a wait you cannot count on: react like a racing driver, with jump starts counted. Free, with no account or uploads.

React when the lights go out

Five lights come on a second apart. Press the moment they all go out; pressing before is a jump start.

How many tries
51020

Press Space or Enter, click or tap the box. A press before the change is too soon; under 100 ms is a guess.

How it works and help
Everything happens in your browser. Nothing is sent anywhere.

A little help along the way

Follow these steps. Every option is explained underneath. Everything happens in your browser; nothing is sent anywhere.

  1. Choose what to react toA colour change is the usual test. A sound, choosing a side and start lights are the others; targets, clicks a second and the spacebar counter test speed of another kind.
  2. Choose how many triesFive tries give a quick score; ten or twenty a steadier one. Clicks are counted over 1 to 60 seconds, and targets in tens.
  3. Press Start, then waitKeep your finger ready. The change comes after a wait that cannot be guessed. Press Space or Enter, click or tap the box the moment it comes.
  4. Read your resultYour middle try comes first, then the average, the fastest and slowest, every try, and what your setup adds.

Questions people ask

How do the start lights work?
Five red lights come on one a second, then all go out together after a wait you cannot count on. Press the moment they go out; pressing while they are on is a jump start.
Is this the same as a Formula 1 start?
It follows the same idea of five lights going out, drawn by KeepSimp. Racing drivers react to lights in about a fifth of a second; your screen and mouse add their own delay here.
What counts as a jump start?
Any press before the lights go out. It is counted and the try is taken again; a press under 100 ms after they go out is counted as a guess.

This page is the Reaction time test, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the Reaction time test's own page.

Read the step-by-step guide

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