Tap the pad to start, then click, tap or press a key the moment the red square appears.
red square
green circle
amber diamond
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 squares after random waits of 1.5 to 5 seconds. Press on each one. Your result is the average in ms.
–This run
–Your best
–Last run
5 signals after a random wait of 1.5 to 5 seconds. Go on the red square. A signal stays for 1.5 seconds. The result is the average of your hits in milliseconds, with the misses beside it. A press before the signal is a false start and the try is repeated.
Brake on the red squareFive red squares after random waits of 1.5 to 5 seconds. Press on each one. Your result is the average in ms.
Long waits, like a quiet roadWaits of 4 to 10 seconds. Attention drifts, and the page times what that costs you.
Space bar as the pedalOnly the space bar counts. Rest a finger on it, as a foot rests near the brake.
Brake or keep going 2
Brake or keep goingTen signals: seven red squares to brake on, three green or amber shapes to ignore. A press on those is a false alarm.
Signal head, brake on redThree lamps in a column, red at the top. Brake only when the top one lights.
Warm up 1
Warm-up, three pressesThree red squares, nothing saved. Learn the pad before a run counts.
Show all 15 rounds and notes (9 more)
From ms to metres 9
0.67 secondsEach Highway Code thinking distance divided by its speed comes to 0.67 seconds, the same at every speed in its table.
100 ms at 30 mph1.34 metres. Multiply by your average in tenths of a second.
100 ms at 70 mph3.13 metres. A 50 ms slower press adds more than 1.5 m on a motorway.
A screen is not a pedalHere your finger is already on the button. In a car the foot moves from the accelerator first, and this page cannot time that.
False alarmA press on green or amber in the decide rounds. It is counted and never timed.
Screen delayA 60 Hz screen redraws every 16.7 ms, so the red square can appear up to that much after the page asks for it.
Thinking distanceThe UK Highway Code gives 9 m at 30 mph and 21 m at 70 mph: the distance covered before the brakes start working.
Two-second gapThe Highway Code asks for at least two seconds behind the car in front on fast roads, doubled on wet roads.
Why the waits are randomA fixed wait can be counted and guessed. A random one makes you react to the signal itself.
How this list was compiled: Rounds and notes written for this page. Thinking distances of 6, 9, 12, 15, 18 and 21 metres at 20, 30, 40, 50, 60 and 70 mph, and the note that the distance depends on your attention: 'Typical stopping distances', UK Highway Code rule 126, https://www.gov.uk/guidance/the-highway-code/general-rules-techniques-and-advice-for-all-drivers-and-riders-103-to-158 and https://assets.publishing.service.gov.uk/media/65f97642aa9b760011fbda4e/the-highway-code-stopping-distances.pdf (both read 2026-09-23). The two-second gap, at least doubled on wet roads, is from the same rule. Computed on 2026-09-23: 1 mph is 0.44704 m/s, so 30 mph is 13.41 m/s and 70 mph 31.29 m/s; each thinking distance divided by its speed gives 0.67 seconds at every speed in the table; 100 ms covers 1.34 m at 30 mph and 3.13 m at 70 mph; a 60 Hz screen redraws every 16.7 ms. Nothing on this page tests fitness to drive. Licence: own work
How it works
This driver reaction time test times how fast you brake on a screen: press when the red square appears, five times, for an average in milliseconds. At 30 mph a car covers 1.34 metres every 100 ms.
Read the full guide
Brake, then decide
Brake on the red square is five presses after random waits. Then play Brake or keep going: press on red, keep still on the green circle and amber diamond. A press on those is a false alarm, counted and never timed.
From milliseconds to metres
The UK Highway Code gives a thinking distance of 9 m at 30 mph and 21 m at 70 mph. At 30 mph each 100 ms of your average is 1.34 m; at 70 mph it is 3.13 m.
Play Long waits, like a quiet road next. Waits of up to 10 seconds show what a wandering mind costs.
A 60 Hz screen redraws every 16.7 ms, so part of every time is the screen's.
Questions and answers
What reaction time does the Highway Code assume?
About 0.67 seconds. Each thinking distance in its table (6 m at 20 mph, 9 m at 30 mph, 21 m at 70 mph) divided by its speed gives that figure. It is a planning figure for real roads, not a score to beat.
Why is a car reaction time test on screen faster than braking?
Here your finger rests on the button and you watch one spot. In a car the hazard can come from anywhere and your foot must move from the accelerator to the brake. This driving reaction time test cannot time that.
Can this test say whether I am fit to drive?
No. It times presses on a screen and nothing else. A slow run can come from a cold start, a laggy mouse or a busy screen. If you are worried about your driving, speak to a doctor or a driving instructor.