An easy way to work out stopping distances

One of the hardest things to remember on the Theory Test is the stopping distances in dry weather on a good surface. Here's a really easy way to remember those distances. Thanks to Mike Pullen for the info on this. It’s already been a great help for a number of people!

20mph = x2 = 40 feet
30mph = x2.5 = 75 feet
40pmh = x3 = 120 feet
50mph = x3.5 = 175 feet
60mph = x4 = 240 feet
70mph = x4.5 = 315 feet

If you remember that 20 is times 2, 40 is times 3 and 60 is times 4, then you can easily work out all the stopping distances from that formula!

(Distances above are approximate only)

Thinking Distance is the same as the MPH that you are travelling at

20mph = 20ft
30mph = 30ft
40mph = 40ft
50mph = 50ft
60mph = 60ft
70mph = 70ft

This leaves how to work out Braking distance on its own.

Work out the overall stopping distance using the formula above. Then take away the thinking distance as explained here.

You are left with the braking distance.

What is the braking distance only when stopping from 40mph?

Overall stopping is (40x3) = 120ft. Thinking distance is 40ft. So braking only distance must be 80ft.