What are the correct UK stopping distances?

Friday 27th September 2019

Knowing the correct stopping distance, braking distance and thinking distance is important to keep safe on the roads. Tailgating – following other cars too closely – is not only one of UK driver’s biggest bugbears, but it’s dangerous, too. Learn how to calculate stopping distances and what affects stopping distances now.

Why is stopping distance important?

By maintaining the correct stopping distance, you will be able to:

• React in time when other motorists need to emergency brake.
• Get a better view of the road ahead
• Manage fuel economy, as stopping in the correct time will help you drive smoothly. This will mean you won’t need to brake harshly, which also saves on fuel costs.

What is stopping distance?

Stopping distance is the total distance it takes your vehicle to come to a complete stop when braking at different speeds. The faster your vehicle is moving, the longer it will take to stop. One of the main things to remember when considering your stopping distance is this formula:

Thinking Distance + Braking Distance = Stopping Distance

Source: The AA

What is thinking distance?

Thinking distance is the amount of time (equated by distance) that it takes for the driver to realise the need to brake in order to react to the hazard directly ahead. According to the official UK Highway Code, and based on a car of around 4 metres in length, thinking distance can be calculated like so:

Source: RAC

What is braking distance?

Braking distance refers to how far your vehicle continues to travel after applying the brakes or undertaking an emergency stop. Based on a car of around 4 metres in length, braking distance can be calculated like so:

Source: RAC

How to calculate stopping distance

This is a common question on driving theory tests. Being able to calculate stopping distances will not only help you pass your test, but allow you to keep safe on the roads long after you’ve passed, too. If you’re wondering how to work out stopping distance, the below calculations can help. However, it’s important to note these are based on an average-sized family car in normal weather conditions, and that the driver is not distracted or impaired. To work this out, it is important that you are familiar with the stopping distance formula: 

Starting from 20mph, simply multiply 10mph speed intervals by 0.5, beginning with 2, for example, 2, 2.5, 3, 3.5 etc, as follows:

• 20 mph x 2 = 40 feet (12 metres or 3 car lengths)
• 30 mph x 2.5 = 75 feet (23 metres or 6 car lengths)
• 40 mph x 3 = 120 feet (36.5 metres or 9 car lengths)
• 50 mph x 3.5 = 175 feet (53 metres or 13 car lengths)
• 60 mph x 4 = 240 feet (73 metres or 18 car lengths)
• 70 mph x 4.5 = 315 feet (96 metres or 24 car lengths)

What can affect car stopping distances?

Aside from the stopping distance formula, there are often many other factors that can affect the actual stopping distance of a car:

• Weather – weather conditions can affect stopping distance immensely. In poor conditions, such as heavy rain, braking is slower and the roads are more slippery – which can cause accidents as stopping distances can increase. Poor visibility can also be an issue, meaning you may not be able to clearly see the hazard ahead until you’re almost upon it. Snow and ice cause many issues, and it’s said that stopping in snow when driving at 70mph could take you further than the length of seven football pitches to stop.
• Road conditions – the terrain of the road can also affect stopping distance. After a period of hot weather and rain, roads may be greasy. This is similar to those wintery days of ‘black ice’, which drivers need to watch out for where the road condition looks deceptively dry.
• Car condition – there are multiple elements of the vehicle itself that could affect stopping distances. This can include worn brake pads, poor quality or condition of tyres or tyre tread depth not meeting the legal minimum requirement. Find new tyres to replace worn down tyres today from your local Formula One Autocentres.
• Driver – of course, one of the most important variables to consider is the driver of the vehicle. If the driver is under the influence of alcohol or drugs, they’ll experience an increased reaction time which could prove fatal. Even if the driver is tired, too hot or feels unwell, their reaction time and resulting stopping distance can also be hugely affected.

If you’re worried that the condition of your car brakes or tyres could be compromising your vehicle performance or stopping distances, get in touch with a member of our expert team today.