How far does your car go before it comes to a stop?
Stopping distance is the distance your car travels after you notice a hazard and before it comes to a complete stop, which includes the distance you travel while you think and the distance your car travels after you have pressed the brakes. Use the stopping distance calculator to determine what this distance is for your speed and for the conditions of the road, and get the right tyres for your car in the process.
What is thinking distance?
It is the distance you travel after you have registered the hazard and before you touch the brakes.
What is braking distance?
It is the distance your car travels after you have pressed the brakes. It is determined by grip and speed.
Stopping distance is influenced by tyres
The tread depth, the rubber compound and the pressure all influence the stopping distance, even more so in wet conditions.
Stopping distance calculator
Enter your speed, then choose the road condition and how alert the driver is.
Your speed
Road condition
Driver reaction time
The same speed, three road conditions
Total stopping distance at your chosen speed and reaction time.
What do you need to know about how stopping distance works?
Stopping distance includes thinking distance and braking distance. Thinking distance increases linearly with speed. An attentive driver at a speed of 30 miles per hour will have a thinking distance of approximately 9 metres. At a speed of 70 miles per hour, the thinking distance will be approximately 21 metres.
Braking distance is influenced by the speed of the car, but the influence is not linear. It is a square relationship. This means that braking distance will increase at a far greater rate than speed. This is why, when driving, even a small increase in speed will have a large influence on stopping distance.
Braking distance is influenced by grip too. As an example, consider a road that has recently been rained on. Your braking distance there is almost doubled, but with an icy road, it can be several times longer. Out of everything, the one thing you are fully in control of is your tyres. With good tread, your tyres will clear some water off the road and prevent the tyre from aquaplaning (a type of skidding caused by the water on the road). With worn tread, your braking distance will increase and your tyres may even contribute to aquaplaning. Once you know your size, compare tyres from leading brands or decode your tyre size first.
Highway Code stopping distances
The official stopping distances for a car in dry conditions with an alert driver. These are the figures learner drivers are tested on.
| Speed | Thinking | Braking | Total |
|---|
| 20 mph |
6 m |
6 m |
12 m |
| 30 mph |
9 m |
14 m |
23 m |
| 40 mph |
12 m |
24 m |
36 m |
| 50 mph |
15 m |
38 m |
53 m |
| 60 mph |
18 m |
55 m |
73 m |
| 70 mph |
21 m |
75 m |
96 m |
In the wet your braking distance roughly doubles, and on snow and ice it can be several times longer again. Enter any speed in the calculator above to see your own figures for wet and icy roads.
What affects your stopping distance
Your braking distance is also influenced by your speed. Braking distance increases with the square of speed. Thinking distance depends on the time taken to react, and this can be influenced by factors such as tiredness, distraction and phone use. The state of the road can change the grip that is available. Braking is also influenced by rain, ice, mud and loose gravel. In cold and snowy weather, summer tyres lose grip below approximately 7 °C.
There are also your tyres. The grip you have, especially on a wet road, is deeply influenced by the state of your tyre tread, your tyre rubber and the pressure in your tyres. The legal minimum tread depth is 1.6 mm, but running that low will greatly influence your braking distance at motorway speed. A tyre with fresh tread will stop several car lengths before a tyre at the legal minimum, so it is important to check tread depth before a journey. Worn tyres should be replaced immediately to reduce braking distance.
Stopping distance FAQs
How is stopping distance defined?
By definition, stopping distance is the sum total of thinking distance and braking distance. The thinking distance component is determined by speed and reaction time. The braking distance component is determined by the speed, friction and gravity parameters. Braking distance increases at an accelerating rate as the speed of the vehicle rises.
What is thinking distance and what is braking distance?
Thinking distance describes the distance the vehicle travels while the driver is perceiving a hazard and moving their foot to the brake pedal. Braking distance describes the distance the vehicle travels after the braking system is applied, until it comes to a complete stop.
How much longer is stopping distance in the wet?
A vehicle on a wet road will have a stopping distance that is, on average, twice as long as a vehicle on a dry road. The stopping distance becomes even longer on roads covered by snow and ice, and especially on roads covered by a layer of glass-like ice.
Do tyres affect stopping distances?
Yes. Tyres are the only vehicle component that contacts the road surface. Stopping distance is directly affected by tyre tread, tyre material and proper inflation. A tyre that is worn to the legal limit will stop a vehicle at motorway speeds much more slowly than a tyre that has tread.
What is the stopping distance at 30 mph and 70 mph?
Following the official figures in the Highway Code, the stopping distance for an alert driver on a dry road at 30 mph is approximately 23 m (9 m thinking distance and 14 m braking distance). At 70 mph, the stopping distance is roughly 96 m (21 m thinking distance and 75 m braking distance). In wet conditions these figures will roughly double.
How can I reduce my stopping distance?
Stopping distance can be reduced by driving slower and by leaving a larger gap between your car and the vehicle in front. Your level of alertness improves reaction time, and stopping distance can be affected by the condition of your tyres. Keep the tread depth healthy and the pressure in the recommended range, and replace the tyre when it is near the legal minimum. The condition of your brakes and not overloading your car are also important.
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