How far does your car travel before it stops?
Your stopping distance is how far the car keeps moving from the moment you spot a hazard to the moment you stop - your thinking distance plus your braking distance. Use this free stopping distance calculator to see it for any speed and road condition, then find the right tyres for your car.
Thinking distance
How far you travel while you react, before your foot touches the brake.
Braking distance
How far the car travels once the brakes are on - set by grip and speed.
Tyres decide grip
Tread depth, compound and pressure change how quickly you can stop, especially in the wet.
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.
How stopping distance works
Your overall stopping distance is made of two parts. First comes thinking distance - the distance the car covers while you see the hazard and move your foot to the brake. It grows in a straight line with speed: at 30 mph an alert driver travels about 9 m before braking even begins, and at 70 mph about 21 m.
Second comes braking distance - the distance the car travels once the brakes are on. This rises with the square of speed, so it climbs far faster: doubling your speed roughly quadruples the braking distance. That is why a small increase in speed makes such a big difference to how far you need to stop.
Braking distance also depends on grip. On a wet road it can roughly double, and on ice it can be several times longer again. The single biggest thing you control is your tyres: healthy tread clears water and holds the road, while worn tread lets wet braking distances grow sharply, and low tread can even let the tyres aquaplane in standing water. 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
Speed matters most, because braking distance rises with the square of speed. Reaction time stretches the thinking distance - tiredness, distraction and phone use can easily double it. Road conditions change the grip available: rain, ice, mud and loose gravel all lengthen braking. In cold or snowy weather, winter tyres or all-season tyres keep grip that summer rubber loses below about 7 C.
Then there are your tyres. Tread depth, rubber compound and correct pressure decide how much grip you actually have, especially on a wet road. A tyre at the legal minimum of 1.6 mm can take several car lengths longer to stop from motorway speed than a tyre with fresh tread, so it is worth learning how to check your tread depth with the 20p test. If your tyres are worn, replace them promptly to keep your stopping distances short.
Stopping distance FAQs
How is stopping distance calculated?
Stopping distance is thinking distance plus braking distance. Thinking distance is your speed multiplied by your reaction time. Braking distance is your speed squared, divided by twice the grip (friction) and gravity. Because braking depends on speed squared, it grows much faster than thinking distance as you speed up.
What is the difference between thinking and braking distance?
Thinking distance is how far the car travels while you notice a hazard and move your foot to the brake pedal. Braking distance is how far it travels after the brakes are applied until it stops. Added together they give your total stopping distance.
How much longer is stopping distance in the wet?
On a wet road your braking distance roughly doubles compared with a dry road, because there is less grip. On snow and ice it can be several times longer again, and on sheet ice up to ten times. Good tyres with plenty of tread clear water far better, which is why worn tyres are especially dangerous in the rain.
Do tyres affect stopping distance?
Yes, significantly. Tyres are the only contact between your car and the road, so tread depth, rubber compound and correct pressure directly set how quickly you can stop. A tyre worn to the legal 1.6 mm can take several car lengths longer to stop from motorway speed in the wet than a tyre with fresh tread.
What is the stopping distance at 30mph and 70mph?
Using the official Highway Code figures for a dry road with an alert driver, the typical stopping distance is about 23 m (9 m thinking plus 14 m braking) at 30 mph, and about 96 m (21 m thinking plus 75 m braking) at 70 mph. In the wet, expect these to roughly double.
How can I reduce my stopping distance?
Slow down and leave a bigger gap, stay alert to cut reaction time, and keep your tyres in good condition. Check tread depth regularly, keep tyres at the correct pressure, and replace them before they reach the legal limit. Good brakes and not overloading the car also help.
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