Interactive tool · Updated October 2026
Stopping distance simulator
Pick a speed, press play and watch a real car react and brake on an Irish road, in real time. Speed, how fast you react and the road surface each change the answer, often by more than drivers expect.
Section 1
Try it yourself
Pick a speed, the road surface and your reaction time, then press play and watch it in real time. Everything is measured from the moment you spot the hazard. The amber stretch is the road you cover before your foot reaches the brake; the red stretch is the braking itself. The distances come from the stopping distance tables in the RSA Rules of the Road.
Speed 50 km/h
The speeds the RSA gives stopping distances for.
Road surface Dry
The RSA publishes no stopping distances for ice or snow.
Starts at 0.72 s, the reaction time behind the RSA table: it gives exactly the table's reaction distances at every speed (10 m at 50 km/h, 24 m at 120 km/h). Drag right to see a slower reaction; the braking distance stays the RSA's. The RSA says seeing a hazard and realising it is one can take 0.25 to 0.5 of a second, and moving your foot to the brake 0.25 to 0.75 of a second or more, as long as 1.5 seconds. Alcohol, drugs, tiredness, fatigue and lack of concentration slow both down.
The RSA figures are a best case. They assume ideal conditions: a good road surface, good visibility, a car with good brakes and tyres, and a rested, alert driver with a very good reaction time. The RSA calls them absolute minimums: the average stopping distance can be significantly longer.
Section 2
What your stopping distance is made of
The RSA splits it into four things. The first two are down to you; the last two are down to your car.
1. Seeing it, and 2. reacting to it
Perception time is how long it takes you to see a hazard and realise you have to act. The RSA puts it at 0.25 to 0.5 of a second. Reaction time is moving your foot from the accelerator to the brake: 0.25 to 0.75 of a second or more, and as long as 1.5 seconds. Alcohol, drugs, tiredness, fatigue and lack of concentration all slow both down.
reaction distance = speed × time3. Your car responding, and 4. braking
Once you press the pedal, the car takes time to respond. That depends on its condition, the brakes most of all. How hard it can then stop depends on the brakes, the tyre pressure, tread and grip, the weight of the vehicle, the suspension and the road surface.
Double the speed and the braking distance is nearly four times longer. From 50 km/h to 100 km/h on a wet road, the RSA's minimum braking distance goes from 26 metres to 101 metres. Your reaction distance only doubles, because you cover it at a steady speed before the brakes go on.
Why 5 km/h matters
The RSA's own figures for a pedestrian hit by a car: at 60 km/h, 9 out of 10 are killed; at 50 km/h, 5 out of 10; at 30 km/h, 1 out of 10. A 5 km/h difference in your speed could be the difference between life and death for a vulnerable road user.
Not the gap you think
Many drivers believe that if the car in front starts braking, they can react, brake and stop and still leave the same gap. The RSA calls this a false belief. While you are reacting you are still travelling at full speed, and the car in front is already slowing down.
Section 3
The RSA stopping distances
The minimum stopping distances the RSA recommends you allow for a car, in dry and in wet conditions. The reaction distance is the same in both; only the braking changes.
| Speed | Reaction | Braking (dry) | Total (dry) | Braking (wet) | Total (wet) |
|---|
Minimum distances in metres. RSA Rules of the Road (2026 edition), table 5 (dry, p. 123) and table 6 (wet, p. 124). Source: Transport Research Laboratory, UK, 2012, © Road Safety Authority, 2012. The dry table has no rows for 20 or 70 km/h. These figures are a best case: ideal conditions, a good road surface, good visibility, a car with good brakes and tyres, and a rested, alert driver with a very good reaction time. The RSA: these are absolute minimums, and the average stopping distance can be significantly longer.
Section 4
What this means for your following gap
The RSA's rule for the gap to the vehicle in front is time, not metres.
The two-second rule
On a dry road, pick a fixed point such as a lamp post or road sign. When the vehicle in front passes it, say “Only a fool breaks the two-second rule.” If you reach the point before you finish, you are too close: pull back.
Wet, snow, fog and ice
In wet weather, double the gap: say the phrase twice. In snow, fog and ice you may need to say it 4 or 5 times. Never drive closer than the two-second rule allows; if you run into the vehicle in front, you are liable for any damage caused.
Want the full picture on safe following distance?
Our review digs into where the two-second rule comes from, when it holds, and when it quietly fails.
Read the Two-Second Rule reviewSection 5
Common questions
Are these the official Irish figures?
Yes. With the reaction time at 0.72 s, every distance in the simulator is taken straight from the stopping distance tables in the RSA Rules of the Road (2026 edition, pages 123 and 124). Nothing is rounded or recalculated. They are a best case: ideal conditions, a good road surface, good visibility, a car with good brakes and tyres, and a rested, alert driver with a very good reaction time. The RSA calls them absolute minimums: the average stopping distance can be significantly longer.
Why does the reaction time start at 0.72 seconds?
Because that is the time behind the RSA's own reaction distances. At every speed in its tables, the reaction distance is what you cover in 0.72 s: 10 m at 50 km/h, 16 m at 80 km/h, 24 m at 120 km/h. The RSA does not print the 0.72 itself; we worked it out from the tables.
The slider goes up to 4 seconds. The RSA gives perception time as up to 0.5 of a second and reaction time as up to 1.5 seconds, so 2 seconds is both at their longest, and its own example is 4 seconds at 100 km/h: 110 metres before the brakes are applied. When you slow the reaction down, the reaction distance is speed multiplied by the time and the braking distance stays the RSA's.
Why is there no ice or snow option?
The RSA does not publish stopping distances for ice or snow, so we do not make one up. What it does say is about the gap: in snow, fog and ice you may need to say “Only a fool breaks the two-second rule” 4 or 5 times.
What is the car in the picture?
A Toyota Corolla Hatchback, drawn to its real size (4.37 m long), on the left-hand side of the road as in Ireland. The road changes with the speed you pick: an urban road up to 60 km/h, a regional road at 80, a national road with hard shoulders at 100 and a motorway at 120, each marked the way the Rules of the Road describes.
How does this connect to my lessons?
Reading the road and managing your speed before hazards is core to passing your test and to driving safely afterwards. We coach observation and realistic speed choice on every lesson. If you want to understand the deeper mechanics, pair this tool with our physics of braking and cornering guide.
The distances are absolute minimums. Educational tool only. It does not replace the Rules of the Road or qualified instruction.