Stopping Distances: The Highway Code Figures Explained
At 30 mph, the typical stopping distance for a car is 23 metres (about six car lengths); at 70 mph it's 96 metres (about 24 car lengths). Stopping distance is thinking distance plus braking distance, and on wet roads it will be at least double.
What is stopping distance?
Stopping distance is how far your vehicle travels from the moment you see a hazard to the moment you stop. It has two parts:
- Thinking distance: how far you travel between seeing the hazard and starting to brake.
- Braking distance: how far you travel once the brakes are on until the vehicle stops.
The Highway Code gives typical figures for a car in good conditions. They're a general guide: the real distance depends on your attention, the road surface, the weather and the condition of your vehicle.
Highway Code stopping distances chart
| Speed | Thinking distance | Braking distance | Overall stopping distance | Car lengths |
|---|---|---|---|---|
| 20 mph | 6 m | 6 m | 12 m (40 ft) | 3 |
| 30 mph | 9 m | 14 m | 23 m (75 ft) | 6 |
| 40 mph | 12 m | 24 m | 36 m (118 ft) | 9 |
| 50 mph | 15 m | 38 m | 53 m (175 ft) | 13 |
| 60 mph | 18 m | 55 m | 73 m (240 ft) | 18 |
| 70 mph | 21 m | 75 m | 96 m (315 ft) | 24 |
Source: The Highway Code, rule 126 (Open Government Licence v3.0). Average car length 4 m.
The Highway Code uses an average car length of 4 metres (13 feet) to convert these distances into car lengths.
Why braking distance grows so fast
Look at the chart and you'll see that thinking distance rises steadily – 3 metres for every extra 10 mph – while braking distance grows much faster. At 20 mph the two are the same: 6 metres each. At 70 mph you travel 21 metres before you even touch the brake, then another 75 metres while braking.
That's because the energy your vehicle carries rises with the square of its speed. Double your speed and you need roughly four times the distance to brake. It's why a small increase in speed makes a big difference to whether you can stop in time.
Easy ways to remember stopping distances
Thinking distance
Multiply the speed in mph by 0.3 to get the thinking distance in metres. At 30 mph, 30 × 0.3 = 9 metres. At 50 mph, 50 × 0.3 = 15 metres.
Overall stopping distance in feet
Multiply the speed by a number that goes up by 0.5 each time, starting at 2 for 20 mph:
- 20 mph × 2 = 40 feet
- 30 mph × 2.5 = 75 feet
- 40 mph × 3 = 120 feet (the chart says 118)
- 50 mph × 3.5 = 175 feet
- 60 mph × 4 = 240 feet
- 70 mph × 4.5 = 315 feet
The theory test usually gives answers in metres, so learn the metre figures too: 12, 23, 36, 53, 73, 96.
Wet, icy and bad weather
- Wet roads: stopping distances will be at least double those on dry roads, because your tyres have less grip (Highway Code rule 227).
- Icy or snowy roads: stopping distances can be ten times greater than on dry roads, so keep well back (Highway Code rule 230).
- Fog: be able to pull up well within the distance you can see clearly (Highway Code rule 235).
The two-second rule
You can't measure metres on the road, so use time instead. The Highway Code says to leave at least a two-second gap between you and the vehicle in front on high-speed roads and in tunnels where visibility is reduced (rule 126).
- Watch the vehicle in front pass a fixed point, such as a sign or a bridge.
- Count "one thousand, two thousand" at a normal pace.
- If you reach the point before you finish counting, you're too close – drop back.
Double the gap to at least four seconds on wet roads, and allow up to ten times the gap on icy roads. The safest rule of all is never to get closer than the overall stopping distance.
Large vehicles, motorcycles and tunnels
Large vehicles and motorcycles need a greater distance to stop. If you're driving a large vehicle in a tunnel, leave a four-second gap. If you have to stop in a tunnel, leave at least 5 metres between you and the vehicle in front (Highway Code rule 126).
What makes stopping distance longer?
- Speed – the biggest factor of all.
- Tiredness, distraction, alcohol or drugs – all slow your reactions and add to thinking distance.
- Road surface and weather – rain, ice, snow, loose gravel and wet leaves reduce grip.
- Tyres and brakes – worn tyres and brakes increase braking distance. Car tyres must have at least 1.6 mm of tread across the central three-quarters of the tread and around the whole tyre (Highway Code Annex 6).
- Load and gradient – a heavily loaded vehicle or a downhill slope takes longer to stop.
Tailgating
Tailgating means following so closely that you couldn't stop safely if the vehicle in front braked suddenly. The Highway Code calls it dangerous and intimidating, and it can cause collisions, especially at speed. Dangerous and careless driving offences such as tailgating are enforced by the police.
Stopping distances in the theory test
Expect questions asking for the typical stopping distance at a given speed, how weather changes it, and what gap to leave. They often appear in the safety margins topic. Test yourself with our Highway Code test, then try a full mock theory test. For the original chart, see Highway Code rule 126 on GOV.UK.
Figures from The Highway Code, Crown copyright, used under the Open Government Licence v3.0. MockTheory is not affiliated with or endorsed by the DVSA.
Test yourself: stopping distances quiz
Frequently asked questions
What is the stopping distance at 30 mph?
The Highway Code gives a typical stopping distance of 23 metres at 30 mph: 9 metres thinking distance plus 14 metres braking distance. That is about six car lengths.
What is the stopping distance at 70 mph?
The typical stopping distance at 70 mph is 96 metres: 21 metres thinking distance plus 75 metres braking distance, or about 24 car lengths.
What is thinking distance?
Thinking distance is how far you travel between seeing a hazard and starting to brake. In The Highway Code chart it rises by 3 metres for every 10 mph, from 6 metres at 20 mph to 21 metres at 70 mph.
How much longer are stopping distances in the wet?
In wet weather, stopping distances will be at least double those on dry roads. On icy roads they can be ten times greater.
What is the two-second rule?
Leave at least a two-second gap between you and the vehicle in front on high-speed roads. Count it using a fixed point such as a sign, and double the gap on wet roads.
What is the stopping distance at 20 mph?
The typical stopping distance at 20 mph is 12 metres (6 metres thinking plus 6 metres braking), or about three car lengths.
Original practice questions based on The Highway Code (Open Government Licence v3.0). Not the real test questions. MockTheory is not affiliated with or endorsed by the DVSA.