Tap the pad to start, watch five red lights come on, and tap the moment they all go out.
A lamp that is on is filled, and a lamp that is off is a ring. The signal is every lamp going out at once.
This test switches shapes and lamps on and off, never more than three times a second and with no fades. Skip it if flashing lights trouble you.
More options
Five red lights come on one second apart, hold for 1 to 4 seconds, and go out together. Press the moment they go out. Five starts, your average in ms.
–This run
–Your best
–Last run
5 tries. 5 lights come on from left to right, one a second. They stay lit for a random wait of 1 to 4 seconds, then all go out together, and that is the signal. The time runs from the first frame without lights to your press. A press while a light is on is a jump start: the try is repeated and the jump starts are counted. The result is the average of your times.
Best of five startsFive starts, and only your quickest counts. One clean launch is the score, so a slow start costs nothing but a jump start is still taken again.
Five lights, lights outFive red lights come on one second apart, hold for 1 to 4 seconds, and go out together. Press the moment they go out. Five starts, your average in ms.
Ten starts in a rowThe same five lights, ten times. A longer run shows whether your first starts were luck, and the first five are set against the last five.
Change the hold 3
Long hold, 3 to 7 secondsAll five lights stay on for 3 to 7 seconds. The longer the wait, the more the hand wants to go early. Count your jump starts.
Same hold every timeExactly two seconds after the fifth light, every start. You can count it, so presses under 100 ms are void as guesses. Compare it with the random hold.
Short hold, under 1.5 secondsThe lights go out 0.5 to 1.5 seconds after the fifth one comes on. Almost no time to settle before you must go.
Show all 14 rounds and notes (8 more)
Hands and lights 4
Space bar onlyOnly a key press counts. Rest a finger on the space bar through the lights and keep it still until they go out.
Tap or click onlyOnly a click or a tap on the pad counts. On a phone, keep your thumb on the glass and lift it only to tap.
Three quick lightsThree lights half a second apart, then the hold. A short build-up gives you less time to get set.
Warm-up, two startsTwo starts, not saved. Find the pad and the rhythm of the lights before a run that counts.
The start and the score 4
Jump startsA press while any light is still on is a jump start. It is never timed: the start is taken again, and the number of jumps is written in your result.
What lights out meansIn a standing start the cars sit still with engines running. Five lights come on, and after a set number of seconds they go out: that is the start. This page copies the lights, not the car.
What the time includesYour time runs from the frame the lights went out to the press the browser saw, so it includes the screen and the mouse or keyboard as well as you. Compare runs on the same device.
Why the hold is randomIf the lights always went out at the same moment, you could count and go on the beat. A random hold means you have to see them go out. Same hold every time shows the difference.
How this list was compiled: Rounds and notes written for this page. A standing start, with cars still and engines running, a light system of five lights, and the race under way when the lights go out after a set number of seconds; the rolling start, where cars are paced, as the other kind: https://en.wikipedia.org/wiki/Standing_start, read 2026-09-24. The article gives no gap between the lights and no length for the hold, so the one-second gap and the random holds on this page are this site's own choice. That lights come on from left to right, stay lit for the hold and all go out at once, and that a press before they go out is void, taken again and counted, is how this page draws and scores a lights round. Why a random hold stops a guess is this page's own explanation. Nothing on this page tests fitness to drive or anything about health. Licence: own work
How it works
This lights out reaction test copies a standing start: five red lights, a random hold, then all out at once. Your time is the average of five starts in ms. Go early and it is a jump start, taken again.
Read the full guide
Ten rounds of starts
Begin with Five lights, lights out. Long hold, 3 to 7 seconds tempts you to jump. Same hold every time lets you count the beat, then sets your time beside the random hold, so you see what guessing is worth.
Jump starts and your time
A press while a light is still on is a jump start: never timed, taken again and counted in the result. Your time runs from lights out to the press your browser saw, screen and mouse included.
Watch the whole row, not the last light. They all go out together, so a wide view sees it as soon as a narrow one.
Questions and answers
How long do the lights stay on?
The five lights come on one second apart. On the first round they then hold for 1 to 4 seconds, picked at random, before going out. Other rounds change the hold or the number of lights.
Why is my race start time slower than on the green lamp test?
The build-up of lights can make you tense, and a long hold tempts you to guess. Compare with the plain reaction time test on the same device to see the difference.
Is a lights out reaction test a health check?
No. It measures how fast you pressed on this device, screen and mouse included, and it diagnoses nothing. It says nothing about driving either. If you are worried about your reactions, talk to a doctor.