Stopping distance calculator
At 30 mph, the Highway Code’s typical stopping distance is 23 metres, about 6 car lengths. At 70 mph it is 96 metres, and at least double that in the wet.
- Thinking distance
- 9 m
- Braking distance
- 14 m
- Car lengths
- 6
- Two-second gap
- 27 m
At 30 mph on a dry road. About 6 car lengths, based on a 4 m car.
Typical distances for a well-maintained car with an alert driver. Tiredness, distraction and worn tyres all make them longer.
Highway Code stopping distances
Typical distances on a dry road, in metres.
| Speed | Thinking | Braking | Total | Car lengths | Wet road |
|---|---|---|---|---|---|
| 20 mph | 6 m | 6 m | 12 m | 3 | 24 m+ |
| 30 mph | 9 m | 14 m | 23 m | 6 | 46 m+ |
| 40 mph | 12 m | 24 m | 36 m | 9 | 72 m+ |
| 50 mph | 15 m | 38 m | 53 m | 13 | 106 m+ |
| 60 mph | 18 m | 55 m | 73 m | 18 | 146 m+ |
| 70 mph | 21 m | 75 m | 96 m | 24 | 192 m+ |
How we calculate this
Stopping distance is thinking distance (the distance you travel before you react) plus braking distance. Between 20 and 70 mph we use the Highway Code’s published figures. Outside that range we use the formula they follow.
The Highway Code says stopping distances are at least double in wet weather and can be ten times greater on ice. We count a car length as 4 metres. The two-second gap is how far you travel in two seconds, the gap the Highway Code recommends on dry roads.
Questions people ask
What is the stopping distance at 30 mph?
23 metres on a dry road: 9 metres thinking distance and 14 metres braking. That is about six car lengths.
What is the stopping distance at 70 mph?
96 metres in the dry: 21 metres thinking and 75 metres braking, about 24 car lengths. In the wet it is at least double.
What is the two-second rule?
Leave at least a two-second gap behind the vehicle in front on fast roads. Pick a fixed point and count. Double it in the wet, and allow much more on icy roads.
Are these distances accurate for my car?
They are typical figures used for the theory test. Real distances depend on your car, tyres, brakes, the road surface and how alert you are, and are often longer.
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