UK stopping distances made easy
Stopping distances are one of the most failed parts of the theory test because there are six numbers to remember and they are easy to muddle. Here is the full table, what the numbers mean, and a trick that makes them stick.
The full table
Overall stopping distance is your thinking distance (how far you travel before you react) plus your braking distance (how far the car travels once you brake).
| Speed | Thinking | Braking | Overall |
|---|---|---|---|
| 20 mph | 6 m | 6 m | 12 m |
| 30 mph | 9 m | 14 m | 23 m |
| 40 mph | 12 m | 24 m | 36 m |
| 50 mph | 15 m | 38 m | 53 m |
| 60 mph | 18 m | 55 m | 73 m |
| 70 mph | 21 m | 75 m | 96 m |
The memory trick (in feet)
The overall distances follow a neat pattern when you work in feet. Take the speed and multiply it by a number that starts at 2 and goes up by 0.5 each step:
- 20 mph → 20 × 2 = 40 ft
- 30 mph → 30 × 2.5 = 75 ft
- 40 mph → 40 × 3 = 120 ft
- 50 mph → 50 × 3.5 = 175 ft
- 60 mph → 60 × 4 = 240 ft
- 70 mph → 70 × 4.5 = 315 ft
Learn the multipliers 2, 2.5, 3, 3.5, 4, 4.5 and you can rebuild every row in your head. The metre figures in the table above are the official ones the test uses.
The one fact people miss
Braking distance grows far faster than thinking distance. Thinking distance rises in a straight line, but braking distance roughly quadruples when you double your speed. That is why 70 mph is eight times the overall distance of 20 mph, not three and a half times.
Wet and icy roads
- Wet roads: braking distance can double.
- Icy roads: it can be up to ten times longer.
- Following distance: use the two-second rule in the dry, at least four seconds in the wet.
How this shows up in the test
Expect questions that ask for a single distance ("the overall stopping distance at 60 mph is..."), the thinking-versus-braking split, or how the figures change in the rain. Knowing the table plus the wet and icy rules covers almost all of them.
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