Tap the pad to start, watch three ambers come down, and leave on green: click or tap the pad, or press any key.
Each column from the top: pre-stage and stage, the ambers, green, then red. Your lane is the left one. The place of a lamp says what it is, whatever its colour.
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
The standard run. The pre-stage and stage lamps come on, the page pauses for a random 0.6 to 1.3 seconds, then three ambers light from the top 0.5 seconds apart and green follows 0.5 seconds after the last. That is 1.5 seconds from first amber to green. Leave as soon after green as you can. The result is the average of your green-light tries in milliseconds, with your red lights counted beside it.
–This run
–Your best
–Last run
5 tries. The stage lamps come on, the page waits a random 0.6 to 1.3 seconds, then 3 ambers light from the top 500 ms apart and green follows 500 ms after the last. Leave with a click, a tap or any key. A leave before the first amber only repeats the try. From the first amber on, a time under zero is a red light: it counts and is never taken again. The result is the average of your green-light tries, in milliseconds and the way a time slip prints it (43 ms is .043), with the red lights and the spread beside it.
Five-amber tree of 1963The tree as it looked at its national debut in Indianapolis in 1963: five ambers lighting 0.5 seconds apart, then green, with no pre-stage or stage bulbs on the column. That makes 2.5 seconds from first amber to green, a full second longer than today's countdown. Two ambers came off each side in 1986, partly because hood scoops were hiding the bottom one from drivers.
Full tree, five triesThe standard run. The pre-stage and stage lamps come on, the page pauses for a random 0.6 to 1.3 seconds, then three ambers light from the top 0.5 seconds apart and green follows 0.5 seconds after the last. That is 1.5 seconds from first amber to green. Leave as soon after green as you can. The result is the average of your green-light tries in milliseconds, with your red lights counted beside it.
Last amber only, 1971 pro startFor the 1971 season the body that oversees most North American drag racing gave its professional classes a quicker start on the five-amber tree: only the fifth and last amber lit, and green came four tenths of a second later. Here the top four ambers stay dark. It is the ancestor of today's pro tree, which has flashed all of its ambers together since the column was cut to three.
Show all 25 rounds and notes (22 more)
Pick a tree, continued
Pro tree, five triesAll three ambers flash together and green follows 0.4 seconds later, the gap used by most classes that start on a pro tree. There is no rhythm to count, only one flash to answer. It keeps its own best, because a time cut against a 0.4 second gap says nothing about one cut against a 1.5 second countdown.
Pro tree, half-second greenThe same single flash with green 0.5 seconds behind it. The 0.4 second gap is not universal: Wikipedia's article on the tree lists one class, Super Street, that runs its pro tree at 0.5. A tenth of a second sounds small, but if you have drilled the shorter flash, expect to go red here until the longer beat settles.
Top two ambers hiddenThe full tree with a cover drawn over the first two ambers, so the third is the only one you see. Racers have tried the same thing with a blinder in the car. Two of them told a drag racing magazine in 2022 that it fails at night, because the upper bulbs glare or bleed round the edge. One of the two said he now lets the ambers come down and stares at the third.
How you leave 5
Leave on releaseHold the mouse button, a finger or the space bar to stage, and let go to leave. Some drag cars are held on the line by a transbrake, which engages a forward and a reverse gear at once for as long as the driver holds a momentary button, so the launch is a release and not a press. One racer told a drag racing magazine in 2022 that drivers release the button three ways: with the thumb alone, from the wrist or from the elbow. Try each and keep the steadiest.
Rollout 200 ms on a pro treeThe pro tree with a 200 ms rollout added by the page, again a figure of our own choosing. Green is 400 ms behind the flash, so a press 200 ms after the flash leaves exactly on green, and a press made on green leaves 200 ms late. Answer the flash itself and never wait to see green.
Rollout 300 ms, leave on the last amberOn a strip the clock does not see you go until the car has rolled out of the stage beam. With a clock that reads .000 on green there is 0.5 seconds between the last amber and green, so drivers launch when they see the last amber. This round holds your leave for 300 ms after the press, a figure chosen for this page and not measured from any car. A perfect light then needs a press 200 ms after the third amber.
Space bar launchThe full tree with the space bar as your only control, which is as close as a keyboard gets to a button under the thumb. Keyboard times are stored apart from mouse times, because each device adds a delay of its own between the press and the moment the browser hears it.
Touchscreen launchFor phones and tablets: tap anywhere on the pad to leave. This page times the moment your finger lands on the glass, not the moment it lifts, so hover close and keep the movement small. Touch times have their own best and never mix with mouse or keyboard times.
Race the other lane 3
Handicap start, gap changes every tryEvery opponent in a bracket race brings a different dial-in, so the stagger between the two trees is never the same twice. Each try draws a gap between 0.3 and 1.5 seconds and picks at random which lane goes first. The only rhythm you can trust is your own column's.
Handicap start, other lane firstWikipedia's worked example: a car dialled in at 11.30 seconds meets one dialled in at 10.70, so the slower lane's tree starts first and the quicker lane's first amber lights 0.600 seconds later. You are the quicker car. With that gap the other lane's green comes on 0.1 seconds before your own third amber, which is exactly when a wandering eye costs a red light.
Heads-up, both lanes togetherA second column counts down in step with yours, as in heads-up racing, which starts the two drivers at the same moment. The other lane leaves between 10 and 150 ms after green, a range picked for this page and not taken from any racer. After each try the page says who had the better light. Under the first or worst rule, when both cars leave early only the first to go is charged with the red.
Warm up and consistency 3
Long race day, twenty triesTwenty tries in one sitting, scored as the average of your green-light tries. The result also prints your first five beside your last five and counts the red lights across all twenty. A quicker last five that came with fresh red lights is guessing, not improvement. Winning a 64-car elimination bracket takes six trips to the line, so the sixth light matters as much as the first.
Staging practice, three triesThree tries and nothing saved. Use them to learn the order of events: pre-stage lamp, stage lamp, a random pause, then the ambers. At the North American national events our source describes, a clock is running here too. Once one driver has lit the stage lamp, the other has seven seconds to do the same or is timed out and disqualified. Other strips may set their own limit.
Ten tries, middle one countsTen tries scored by the median, so one lucky guess or one sleepy leave cannot move the result. The page also prints your spread: the gap between your quickest and slowest green-light tries. Bracket rules put a premium on consistency over raw speed, and a driver who cuts the same light every time can plan a race round it.
Reading the tree and the slip 8
A perfect light: .000 or .500Current clocks count from green, so a perfect light reads .000. A newspaper glossary from 1994, quoted in Wikipedia's article on bracket racing, gives .500 as a perfect light. That figure fits a clock started at the last amber of a full tree, since green comes 0.5 seconds later. If an old time slip or an old hand quotes five-something lights, take off .500 to compare with this page.
Dial-in, handicap and breakoutIn bracket racing each driver posts a dial-in, the elapsed time they expect to run, and the slower car gets a head start equal to the difference. If both ran their numbers with equal reaction times they would cross the line together. Run quicker than your dial-in and you break out and lose, unless the other driver broke out by more or went red. With the cars evened up like that, the light is the part a driver can practise at home.
Filament bulbs, LEDs and your screenThe body that oversees most North American drag racing changed its trees from filament bulbs to LEDs in 2003. Vibration from the quickest cars had been breaking as many as twenty bulbs a meet, and Wikipedia records that reaction times dropped after the change. Your screen has a lag of its own: a 60 Hz panel redraws every 16.7 ms, so a lamp can appear that long after the page lit it.
Pre-stage and stage lightsRacers call the column of lights the Christmas tree. Two beams cross each lane under it: one on the starting line and one 7 inches (180 mm) behind it. Breaking the rear beam lights pre-stage and shows you are nearly there. Rolling forward another 7 inches breaks the second beam and lights stage. At the national events of the body that oversees most North American drag racing, the tree used since April 2011 shows the two as the top and bottom halves of one blue lamp. Regional and club events still use two pairs of small amber bulbs.
The random pause before the first amberUntil the 2009 season, at the national events of the body that oversees most North American drag racing, the starter pressed a switch to set the tree going, and drivers learned to anticipate it. Now an automatic start takes over once both cars are staged and begins the sequence within 1.3 seconds, after a delay picked at random. This page draws its pause between 0.6 and 1.3 seconds. The 0.6 floor is our own choice.
Shallow staging and rolloutStaging shallow means creeping forward only until the stage lamp flickers on. The elapsed time clock does not start until the car rolls out of the stage beam, so a shallow car is already moving when timing begins. One drag racing blog, published by a parts retailer, puts that at a tenth or two of quarter-mile elapsed time against staging 2 inches further in. It adds that staging depth changes the reaction time as well, and gives no figure for that. Nor does this page.
Two clocks: reaction time and elapsed timeGreen shows only that the car did not leave early. Reaction time runs from green until the car leaves the stage beam, and the elapsed time clock starts at that moment, so a driver could sit on a green light all day without hurting the elapsed time. In a heads-up race with no breakout rule, the win goes to the lower total of the two. When a slower car wins on its driver's light alone, racers call it a holeshot win. This page measures only the first clock.
What a red light costsLeave before green and the red lamp at the foot of your column lights instead. It is recorded as a negative reaction time, such as -.015. In eliminations a red light loses the race unless the other driver commits a worse foul, such as crossing a lane boundary. In qualifying it is ignored. This page counts your reds beside your average and never hides them.
How this list was compiled: Rounds and notes written for this page. Every round changes one thing about the standard full tree run (the countdown, the way you leave, a rollout delay added by the page, a second lane, or the scoring), so two results can be compared fairly. The arithmetic was computed on 2026-09-19: three ambers 0.5 s apart with green 0.5 s after the last make 1.5 s from first amber to green, and five ambers make 2.5 s, one second longer; an 11.30 dial-in minus a 10.70 dial-in is a 0.600 s head start; with that gap the far lane's green lights at 1.5 s and the near lane's third amber at 1.6 s, 0.1 s apart; a 500 ms amber-to-green gap less a 300 ms rollout, and a 400 ms gap less a 200 ms rollout, both leave 200 ms; a 64-car elimination bracket takes six wins; 7 inches is 178 mm (the source rounds it to 180 mm); one refresh at 60 Hz lasts 16.7 ms. The 0.6 s floor of the pause before the first amber, the 300 ms and 200 ms rollout figures and the other lane's 10 to 150 ms leave are choices made for this page and are not measurements of any car or driver. Facts checked on 2026-09-19. The column of seven lights, the two beams 7 inches (180 mm) apart, pre-stage and stage, the blue lamp halves used at one body's national events since April 2011 and the small amber bulbs still used at regional and club events, the full tree (ambers 0.5 s apart, green 0.5 s after the last), the pro tree (green 0.4 s after the flash, Super Street 0.5 s), the staggered handicap start and its 10.70 against 11.30 example, red lights and which car is charged, a red light being ignored in qualifying, the seven-second staging limit, the automatic start within 1.3 seconds with a random delay and the starter's switch before 2009, the five-amber tree of 1963 and its Indianapolis debut, the 1971 professional start on the last amber alone, the cut to three ambers in 1986, the change from filament bulbs to LEDs in 2003 and the drop in reaction times that followed, and what the green light indicates: https://en.wikipedia.org/wiki/Christmas_tree_(drag_racing). One body overseeing most North American drag racing events (the article on the tree ties the 1986, 2003, 2009 and 2011 changes to that body, which this page does not name), the winner being the first across the line unless a breakout rule applies, reaction time measured from green to the vehicle leaving the staging beams, elapsed time measured separately, the holeshot win, heads-up racing, first or worst, negative times for red lights, dial-in, handicap and breakout, a staged car being free to leave the pre-stage beam, and the premium on consistency: https://en.wikipedia.org/wiki/Drag_racing. The 1994 newspaper glossary that gives .500 as a perfect light, and a false start counting only once the tree is activated: https://en.wikipedia.org/wiki/Bracket_racing. A transbrake engages a forward and a reverse gear together while the driver holds a momentary button: https://en.wikipedia.org/wiki/Transbrake. A .000 starting system with 0.500 s between the last yellow and green, launching on the last yellow, the elapsed time clock waiting for the car to leave the staged beam, shallow staging as a running start at the clocks, a photo caption's tenth or two of quarter-mile elapsed time between shallow and 2 inches in, and staging affecting reaction time as well as elapsed time, with no figure or direction given (Evan J. Smith, 7 January 2026, on a blog published by a parts retailer): https://www.onallcylinders.com/2026/01/07/driver-mod-the-ins-outs-of-drag-racing-for-beginners/. Two racers on blinders over the top bulbs failing at night (glare and bleed round the edge), one of them staring down the third bulb, and one racer's three ways of releasing a transbrake button (Todd Silvey, 17 January 2022): https://www.dragzine.com/features/mastering-the-cockpit-starting-line-advice-for-your-reaction-times/. This page is not connected with any sanctioning body, racing series, track or timing equipment maker. Licence: own work
How it works
This drag racing reaction time test stages you under the starting tree racers call the Christmas tree: stage lights, three ambers, then green. Pick a full tree, ambers 0.5 seconds apart, or a pro tree, all three at once. Five tries give your average in milliseconds, with red lights counted.
Read the full guide
Staging, ambers, green
Tap the pad on Full tree, five tries, first in the Round menu. The stage lamps light, the page waits a random 0.6 to 1.3 seconds, and the ambers come down: 1.5 seconds from first amber to green. Click or tap the pad, or press any key, to leave. After green you are timed in ms: 43 ms also prints as .043. A leave before the first amber only repeats the try. From first amber to green it is a red light: counted, shown as a negative time, never retaken.
Why racers leave on the last amber
On a strip the reaction clock runs from green until the car rolls out of the stage beam. So drivers launch on the third amber and let the car use up the 0.5 seconds. A browser has no car, so the standard round has you hit green itself. Rollout 300 ms, leave on the last amber adds a fixed delay of our choosing to practise that habit.
Two racers told a drag racing magazine in 2022 that covering the top two ambers fails at night. Top two ambers hidden tests the idea.
In Handicap start, other lane first the far lane's green lights 0.1 seconds before your own third amber. Pick your column and never look across.
Judge a run by its red lights and its spread (slowest green-light try minus quickest), not only its average.
Questions and answers
What is the difference between a full tree and a pro tree?
A full tree lights its three ambers 0.5 seconds apart, with green 0.5 seconds after the last. A pro tree flashes all three together, with green 0.4 seconds later in most classes. Handicap starts, where the slower car's countdown begins first, normally run on the full tree.
Is a perfect reaction time .000 or .500?
It depends on the clock. This page counts from green, as current timing does, so a perfect light is .000. A 1994 newspaper glossary gives .500, which fits a clock started at the last amber of a full tree.
Does a slow light mean something is wrong with my reflexes?
No. A poor run can come from a short night, an unfamiliar mouse or a laggy screen. This page diagnoses nothing and cannot predict your light in a real car. If your reactions worry you for a health reason, see a doctor.