Stopping distance is one of the most crucial aspects of car safety and takes into account all sorts of variable factors.
In this guide, we talk about what exactly stopping distance means and how you can calculate it under various conditions.
What is stopping distance?
Stopping distance refers to the distance a vehicle will travel between when its brakes are fully applied and when it comes to a complete stop.
The Driver and Vehicle Standards Agency (DVSA) has laid out current estimate lengths a car is expected to travel when stopping at various speeds. These stopping distance measurements factor in what are called the thinking distance and the braking distance.
As the names suggest, the thinking distance refers to the distance a vehicle will travel when the driver thinks to apply the brakes and takes this action. The braking distance refers to how far the car will travel while slowing eventually to a standstill once the brakes are applied. The thinking distance is estimated at one foot for every mile per hour (mph) you’re travelling at.
For those currently learning to drive, knowing the average stopping distances for cars is useful, since questions on this matter are included in the DVSA’s current question bank for the theory test.
What is the stopping distance at 70mph?
It is estimated that on a typical, dry road, a typical car travelling at 70mph has a stopping distance of 96 metres or 314 feet.
To add some more perspective to those figures, this stopping distance is measured as the equivalent of 24 car lengths. If you were to line up 24 cars together single file, then the length these would cover would be virtually the same a car would cover while stopping from 70mph.
The 96 metres needed to stop a car at 70mph includes 21 metres needed for thinking distance and 75 metres for braking distance.
What is the stopping distance at 60mph?
A car’s stopping distance while travelling at 60mph is estimated at 73 metres (240 feet) or 18 car lengths in total.
This figure combines 18 metres for thinking distance and 55 metres for braking distance.
What is the stopping distance at 50mph?
A car’s stopping distance while travelling at 50mph is estimated at 53 metres (175 feet) or 13 car lengths in total.
This figure combines 15 metres for thinking distance and 38 metres for braking distance.
What is the stopping distance at 40mph?
A car’s stopping distance while travelling at 40mph is estimated at 36 metres (118 feet) or nine car lengths in total.
This figure combines 12 metres for thinking distance and 24 metres for braking distance.
What factors affect stopping distance?
As noted above, speed is an obvious influence on a car’s stopping distance, but weather conditions also majorly alter distances.
Groups like the DVSA estimate that whatever speed a car is travelling at, the overall stopping distance will at least double if you’re driving in wet conditions. If the weather conditions are icy then the overall stopping distance will be at least ten times the average figure.
So if, for example, you are travelling at 50mph in your car and the road is wet, you’ll want to double the standard figures given for stopping distance.
For more tips on driving safely in various weather conditions, check out our guides on driving in snow and ice, driving in wet weather and driving in the fog.