The 2 second rule is a method used to gain a safe following distance at any speed and is also an easy system for all drivers to remember and to put into action.
The rule is very simple and easy to understand by using the description and diagram below. Remaining at least 2 seconds from the vehicle in front will provide a distance of one car length per 5 mph, at which ever speed you drive. The 2 second rule is used regardless of speed because the distance between your vehicle and the one in front will extend the faster you travel. Using the 2 second rule helps to significantly reduce accidents or reduce collision damage if one occurs.
Using this rule provides not only a general safer way of driving, but can also help to save fuel, brake wear and paint damage as a result of stone chips occurring due to driving too close to the car in-front. See how to save petrol for further information.
The 2 second rule should also be utilised by the learner driver as the driving test examiner will most certainly fail your driving test for driving too close to a vehicle (tailgating), or remaining close to the vehicle for too long. Although the 2 second rule applies at any speed, it should only be used on dry roads with ideal driving conditions. Other rules are detailed below.
How to do the 2 second rule
- You are driving along a relatively straight road. To estimate the minimum and safe following distance, allow the car in front (the yellow car) to pass a fixed object. This can be any object that is easy to distinguish such as a road marking or lamp post, although in this case in the diagram, it’s a road sign.
- As the rear of the car in front roughly lines up with your chosen reference marker, count to 2 seconds. If before you have reached 2 seconds your vehicle has passed the same reference marker, you will need to increase your following distance and try again. The 2 second rule isn’t just for the car in front however. If a car is driving too close behind you (tailgating), you will also need to take their thinking distance into account by leaving a sufficient and safe distance between yourself and the car in-front.
Why Follow the 2 Second Rule
By following the 2 second rule, if the car in front of you brakes sharply, you will be able to slow down in good time, but also allow plenty of time for the car behind you to slow down. It’s also essential to learn safe braking techniques such as progressive braking. Progressive braking once learned allows for safer driving and less wear and tear on your vehicle.
What is the 4 Second Rule?
The 4 second rule is essentially the same technique as the 2 second rule, except 4 seconds are used due to weather / road conditions. Generally if the conditions are wet, the 2 seconds should be doubled to 4 seconds to allow for longer braking distances due to slippery roads.
What is the 10 Second Rule?
The 10 second rule should be used for more extreme weather and road conditions where far greater stopping distances are required. Use the 10 second rule where roads are frosty, icy or have snow coverage.
Thinking distance, braking distance and stopping distances
Further information can be found for a cars stopping distance in various weather conditions, at various speed limits. Stopping distances are a necessary part of the theory test questions and is used alongside the 2 second rule for safer driving.
2 Second Rule For Learner Drivers
Practice the 2 second rule as often as possible and before long, you will find that you maintain a safe following distance without need of practicing this technique. During the driving test it is acceptable to drive too close to a vehicle when for example:
- immediately when you join a dual carriageway
- following a vehicle after making a turn
- following a vehicle after moving off from a stationary position
It is important after these situations to impose the 2 second rule as soon as is safely possible, with safe regard to the vehicle behind.
Thank you Nageswara. It’s always good to know that we are helping.
very informative!
The two second rule as illustrated can be very misleading. It is relative to speed. The picture shown would only be true if someone is driving around 25mph, not 55mph. It is far easier IMHO, to gauge the distance by the number of cars between you, instead of getting distracted and trying to gauge by a marker on the side of the road. The rule is therefore more safely accomplished by one car length per every 10mph. So, if you are driving 55-60mph, there should be six car lengths between you in normal driving conditions and even more in wet or other unsafe driving conditions, like heavy traffic.
Hello Charles,
Yes it is relative to speed, which is why it works at all speeds. So at 25 mph, based on the 2 second rule this will be a distance of around 75 feet between you and the car in front. At 55 mph it will be a distance of around 165 feet between you and the car in front. Also, trying to work out car lengths whilst traveling at 55 mph is very difficult from the view of the driver. Simply choosing a marker that the car in front is passing and using the 2 second rule is far less distracting than trying to work out car distances from an awkward angle.
I find that even at 3 seconds in the dry, my Zafira needs an emergency stop if the car in front slams on their brakes (stopping distance of 105ft from 30mph on level ground and dry). Ironically I have learnt that for small hatchbacks, such as Abarth 500 or other small hot hatch things I should be 5 seconds behind but never closer than 3 to anything, regardless of how good the conditions are, anything sporty can stop on a dime.
I general I’m 3 seconds avg dry and 6 wet, although my wet 30mph stopping distance is 125ft, only 20ft more than dry.
I think your website is the most informative resource to pass the theory test with flying colours. The way things have been explained here make this website equally helpful for the practical aspect of the driving too.
I have a question regarding 10 SECONDS RULE mentioned at https://www.drivingtesttips.biz/2-second-rule.html.
My understanding is that the stopping distance for an icy condition is 10 times the stopping distance for a normal condition and therefore for an icy condition, the 2-seconds rule should be converted into a 20-seconds rule (2 seconds * 10 = 20 seconds) instead of 10 SECONDS RULE. Please correct me if I am wrong.
Hi Arvind,
Glad you’re finding the tutorials useful. You’re not wrong, the greater the distance the better, particularly in icy conditions. Though realistically on today’s congested roads, drivers would be very unlikely to leave a 20 second gap.
I was driving during a spell of very heavy rain. It followed a long heat wave without rain, so the road was probably oily. It was daytime. Visibility was poor. I was on a three-lane dual carriageway, traffic was very light. I was travelling at 50mph on the inside lane (slow lane). The speed limit was 50mph. I detected a car in the distance in my lane. It was a long way away – more than 10 seconds away. It became apparent that the car had stopped. By the time I could see this I was getting close. I slowed down, but my wheels locked – even with light pressure. I released the brakes to regain control. I checked my mirrors to make sure it was safe to pull -out, in order to overtake. It was clear. I steered around the stranded car. 10 seconds was barely enough to detect there was a problem ahead, overcome the problem of my brakes locking – bearing in mind I was attempting a gentle slow-down – not harsh braking, and to check the mirrors to make sure nothing was overtaking me. My tyres were good. The 10 second rule is good advice. It sounds like excessive caution, but at times 10 seconds might not be enough. If a line of traffic had been overtaking me, I might not have been able to steer around the car.
Hi Zrzavy,
Good advice. I think the problem is that many people struggle to follow the 2 second rule, let alone 10 seconds.
Extra Ordinary information and Excellent guidance through this web site and Very useful for the beginners as well as for the learners also and definitely I can say “regular driving owners also miss some points” if they don’t read this
If we question the basis of this 2 Second Rule, and regard this as : Duration From Current Traveling Speed to a Complete Stop: Eg, The Vehicle in front fit on something ahead and stopped abruptly:
(With this indication, the assumption that the Vehicle in front will still move forward is removed)
Then
1) What is the basis of coming up with this 2-Second Rule?
2) What is the proof and the physics behind this 2-Seconds rule?
Please also let me share some basic physics calculation for reference: It shows, the higher the speed, the more the seconds to stop the vehicle completely.
The 2 Seconds Rule for all speed (assuming duration for coming to complete stop), needs to be examined, as below shows otherwise:
t = V/a
where t = time in seconds,
V = Initial Speed,
a = Deceleration (normal motorist can achieve is at 0.5 G, or 0.5 * 9.8 m/s^2 or 4.9 m/s^2) (Prof motorist is at 1 G, as they can stop with better deceleration). 1 G = 9.8 m/s^2
We use normal motorist in below calculation.
case A)
V = initial velocity of vehicle, take it as 36 km/h or 10 m/s
a = deceleration, for normal motorist , that will be -0.5 G, or -0.5 * 9.8 m/s^2, or -4.9 m/s^2.
that works out to be: t = 10/4.9 = 2.04 seconds to stop completely from 10 m/s (36 km/h)
case B)
V = initial velocity of vehicle, take it as 72 km/h or 20 m/s
a = deceleration, for normal motorist can achieve , that will be -0.5 G, or -0.5 * 9.8 m/s^2, or -4.9 m/s^2.
that works out to be: t = 20/4.9 = 4.08 seconds to stop completely from 20 m/s (72 km/h)
case C)
V = initial velocity of vehicle, take it as 90 km/h or 25 m/s
a = deceleration, for normal motorist , that will be -0.5 G, or -0.5 * 9.8 m/s^2, or -4.9 m/s^2.
that works out to be: t = 25/4.9 = 5.1 seconds to stop completely from 25 m/s (90 km/h)
Hello BH,
You’re way over thinking this. The 2 second rule is a good general guidance for learner drivers (and all drivers) to have something to work with in terms of a safe stopping distance. There’s no point in saying a specific distance because how do you judge that while driving? You can throw all the physics you want at it, but it’ll make no sense to anyone while they’re driving. Besides, all cars have different stopping distances and all people react at different rates, so there’s really no point for getting into specifics.
Thank you for this site. I am happy to be here and I can confirm I have learnt a lot.
However, please kindly tell me in a clear term what should be my stopping distance to a car in front of me on traffic? ie at what distance should I stop if joining a traffic? 2meters or more? And please, what do I use to measure this from my own car?
Thank you
Hello BM,
Glad that you’re finding the site useful. If I understand your question correctly, are you referring to stopping in traffic and the distance from the vehicle in front? The easiest method to gain an understanding of this is the ‘tyres and tarmac’ rule. It’s a simple visual guide to follow. When you stop, ensure that you can still see the tyres of the vehicle in front, plus around 1 metre or so of tarmac. It doesn’t have to be exact as there’s no specific rule that examiners go by. You can find more information on the stopping in traffic page.
Excellent site for reference, do you know of a motorcyclist instructor that could give similar advice based on riding as opposed to driving? Although in principle the rules are similar the additional experience and advice would be triffic. I’m still laughing at Mr Professor of Physics and Mathematics!! What a Wally!
Hi Ally,
Thanks for your comments. We generally just provide advice on driving cars and the car driving test, but the motorcycle two second rule does follow the same principles as you say. Yes, Mr Professor of Physics and Mathematics might be right in that the 2 second rule does actually become less effective the faster you go, but the whole point of it is that it provides and easy system to visually gauge a safe following distance and though not perfect, it does represent safer following distances than what we often see on our roads.