UK driving theory test · Learn · 2 November 2026 · 6 min read

Highway Code stopping distances from 20 to 70 mph: thinking and braking distance, metres and car lengths, the two-second rule, and wet and icy roads.

At 30 mph a car needs about 23 metres to stop, and at 70 mph about 96 metres, according to The Highway Code's typical stopping distances. Each figure is thinking distance plus braking distance, and both grow with speed, but braking distance grows much faster. On a wet road you need at least double the distance, and on ice it can be ten times as much.

Stopping distances are a staple of the theory test, and safety margins was one of the three topics DVSA named in 2016 as most often answered wrongly. This guide gives the official figures, shows a simple way to remember them, and explains how the gap rules and weather fit in.

The official figures

The Highway Code's Typical stopping distances diagram, linked from Rule 126, gives these figures for a car:

The diagram uses an average car length of 4 metres (13 feet). It also says the figures are a general guide: the real distance depends on your attention (which affects thinking distance), the road surface, the weather and the condition of your vehicle.

Thinking distance and braking distance

Thinking distance is how far you travel between seeing a hazard and starting to brake. You are still moving at full speed while your brain reacts and your foot moves to the pedal. The Highway Code diagram ties it to your attention, so anything that dulls attention, such as tiredness or distraction, makes it longer.

Braking distance is how far the car travels from the moment the brakes are on until it stops. It depends on speed, tyres, brakes, the road surface and the weather.

Add the two together and you get the overall stopping distance, which is the figure most theory test questions ask about.

An easy way to remember them

You do not need to memorise eighteen numbers. Two patterns in the table do most of the work.

Thinking distance goes up by 3 metres for every 10 mph

6, 9, 12, 15, 18, 21. Start at 6 metres for 20 mph and add 3 metres for each extra 10 mph. If you know the speed, you know the thinking distance.

Braking distance grows much faster

6, 14, 24, 38, 55, 75. Braking distance is the same as thinking distance at 20 mph, but by 70 mph it is more than three and a half times as long. Double your speed from 30 to 60 mph and braking distance rises from 14 to 55 metres, roughly four times as far. That is the real lesson of the table: speed costs far more stopping room than people expect.

Learn the totals by heart

For the test, the totals are what count: 12, 23, 36, 53, 73, 96. Say them out loud with their speeds a few times a day for a week. Many learners also remember the car lengths, 3, 6, 9, 13, 18, 24, which are easier to picture on the road.

The two-second rule

On the road you cannot measure 53 metres, so The Highway Code gives a time gap instead. Rule 126 says you should:

• never get closer than the overall stopping distance to the vehicle in front;
• leave at least a two-second gap on high-speed roads and in tunnels where visibility is reduced;
• at least double the gap on wet roads, and make it up to ten times greater on icy roads;
• remember that large vehicles and motorcycles need a greater distance to stop.

To measure two seconds, pick a fixed point such as a sign. When the vehicle ahead passes it, you should not reach it until two seconds later.

Tunnels

Rule 126 adds two tunnel rules. If you drive a large vehicle in a tunnel, allow a four-second gap. If you have to stop in a tunnel, leave at least a 5-metre gap behind the vehicle in front.

Weather changes everything

So 23 metres at 30 mph on a dry road becomes at least 46 metres in the wet. On ice, it could be over 200 metres. Rule 235 also warns that following another car's rear lights in fog can give a false sense of security.

Other times you need more room

• Towing: your stopping distance may increase significantly (Rule 98).
• Motorways: keep a safe distance and increase the gap on wet or icy roads, or in fog (Rule 260).
• Slow-moving traffic: you can close up to keep traffic moving, but never so close that you cannot stop safely (Rule 151).
• Being overtaken: if someone overtakes and pulls into the gap in front of you, drop back to restore a two-second gap (Rule 168).

Tailgating, where the gap is too small to stop safely if the vehicle in front brakes, is dangerous and intimidating, and The Highway Code notes that dangerous and careless driving offences such as tailgating are enforced by the police.

Typical theory test questions

Questions on this topic usually ask you to:

• give the overall stopping distance at a stated speed on a dry road;
• say how much stopping distances increase in the wet or on ice;
• choose the minimum gap on a fast road or in a tunnel;
• name factors that affect thinking or braking distance.

If you know the six totals, the two-second rule and the "double in the wet, ten times on ice" rule, you can answer almost all of them.

How to use this

1. Read our Safety margins chapter, which sets these figures beside the Highway Code rules on weather.
2. Drill the topic with the safety margins drill until you get every stopping distance question right.
3. Read Vehicle handling for braking, skids and driving on ice, which link closely to stopping distances.
4. Take a full practice test, such as practice test 2, to see the topic mixed in with the rest.
5. See how the test is scored in our guide to the UK theory test format.

Source: The Highway Code (gov.uk/guidance/the-highway-code), Rules 98, 126, 151, 168, 227, 230, 235 and 260 and the Typical stopping distances diagram; DVSA news, 1 July 2016; contains public sector information licensed under the Open Government Licence v3.0; checked 1 November 2026.