Why are stopping distances important for the theory test?
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Stopping distances matter because the theory test expects you to know how far a car travels before it stops – and to keep a safe gap so you can stop in time. Several questions in the “Safety margins” topic are based directly on the Highway Code table.
Typical stopping distances (dry road, car)
| Speed | Thinking distance | Braking distance | Total stopping distance |
|---|---|---|---|
| 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 |
Thinking distance is how far you travel before you react; braking distance is how far you travel once the brakes are on. Notice that doubling your speed more than doubles the braking distance.
Bad weather
- On wet roads, stopping distances can be at least double.
- On icy roads, they can be up to ten times greater.
The two-second rule
On a fast road in good conditions, leave at least a two-second gap to the vehicle in front. Double it to four seconds on wet roads, and leave even more in ice and snow.
Test yourself on safety margins with our free practice questions. Source: the Highway Code, rule 126.
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