How to remember stopping distances

Theory Test Stopping Distances

Here are the stopping distances as quoted in the Highway Code. These distances can be difficult to remember but here is a formula to make it easier

What Does Stopping Distance Mean?

Stopping distance is the total distance a vehicle travels from the moment a driver spots a hazard to when the car comes to a complete stop. It consists of two parts: thinking distance (the distance covered while the driver reacts) and braking distance (the distance it takes to stop after the brakes are applied). You can estimate the total distance in feet by multiplying your speed by a factor—starting at 2 for 20 mph and adding 0.5 for every 10 mph increase. For example, at 30 mph: 30 × 2.5 = 75 feet.

How to remember stopping distances.

A typical question in the theory test is: “What is the overall stopping, thinking, or braking] distance at 30 mph?”

Instead of memorising a list of distances, you can calculate them using the method explained below. This method gives the distance in feet, which you can convert to metres if needed.

To remember stopping distances, it’s pretty straightforward 20mph x2, 30mph x 2.5, 40mph x 3 and so on.. Start with 20 mph and multiply that by 2 for the stopping distance, then for 30 mph multiply by 2.5, and just keep going up by half for every additional 10 mph

If the road’s wet, just double those stopping distances, but if you’re dealing with ice or snow, you’ll want to multiply by 10, which means if you’re cruising at 30 mph in the snow, you might need up to 60 car lengths to come to a stop!

Be careful to read the questions correctly on your theory test as you may be asked the thinking distance, the braking distance or the overall stopping distance. Again you can use the same formula, just remember that the thinking distance is always the same as the speed, I.E

Thinking Distance

20mph thinking distance = 20 ft.

30mph thinking distance = 30 ft.

40mph thinking distance = 40 ft.

And so on.

So at 40 mph the overall stopping distance will be (40 x 3 ) 120 feet so if we deduct the thinking distance which would be 40 feet, this leaves us with the braking distance of 80 feet.

Obviously this wont help much in an emergency, but it is a great way to memorise the figures for your theory test.

Pay close attention to how questions are worded in your theory test—they may ask for thinking distance, braking distance, or the total stopping distance. Luckily, you can use a simple method to work them out. Thinking distance is easy: it’s the same as your speed in feet (e.g. 20 mph = 20 ft, 30 mph = 30 ft). To estimate total stopping distance, multiply your speed by a factor (at 40 mph, use ×3 = 120 ft). Subtract the thinking distance (40 ft), and you get a braking distance of 80 ft. It’s not for emergencies—but it’s perfect for the theory test!