141 stopping distances — from 10 to 150 km/h
Double the speed and the braking distance quadruples. Here is the ground covered before the pedal moves, and the ground covered after it, on four kinds of surface.
At the posted limits
This is where a 30 km/h school zone and a 50 km/h city street part ways: 20 km/h apart in speed, but twice the stopping distance.
Twice the speed, four times the distance
Braking distance grows with the square of speed, because the energy of a moving car grows with the square of speed — and the brakes have to shed all of it.
The car moves before the pedal does
It takes about a second to see the danger and move your foot. At 100 km/h that second carries you 28 metres with the brakes still untouched.
The surface decides half of it
At the same speed, ice takes six or seven times the distance of dry asphalt, simply because the grip is that much lower.
| Speed | dry asphalt | wet road |
|---|---|---|
| 10 km/h | 3.3 m | 3.6 m |
| 20 km/h | 7.6 m | 8.7 m |
| 30 km/h | 12.7 m | 15.4 m |
| 40 km/h | 19 m | 23.7 m |
| 50 km/h | 26.2 m | 33.6 m |
| 60 km/h | 34.4 m | 45 m |
| 70 km/h | 43.5 m | 57.9 m |
| 80 km/h | 53.7 m | 72.5 m |
| 90 km/h | 64.8 m | 88.7 m |
| 100 km/h | 77 m | 106.5 m |
| 110 km/h | 90.1 m | 125.8 m |
| 120 km/h | 104.1 m | 146.6 m |
| 130 km/h | 119.2 m | 169 m |
| 140 km/h | 135.3 m | 193.1 m |
| 150 km/h | 152.3 m | 218.7 m |
From 10 to 150 km/h
How to read this
- Stopping distance = reaction distance + braking distance.
- Reaction distance is one second of travel, so it grows in step with speed.
- Braking distance is speed squared ÷ (2 × grip × 9.81).
- A heavier car brakes in the same distance — mass cancels out of the equation.
These are estimates. They assume a one-second reaction and a representative grip for each surface; real distances shift with tyres, brakes, slope and load.
Frequently asked questions
Q. Does a heavier car slide further?
No. More mass means more energy, but also more grip pressing on the road, and the two cancel in the equation. In practice a heavy vehicle can stop longer once the brakes overheat.
Q. Where does the one-second reaction come from?
It is the figure road-safety courses use. Real reactions scatter between roughly 0.7 and 1.5 seconds, and stretch further when a driver is tired or looking away.
Q. Does ABS shorten the distance?
Not necessarily. ABS keeps the wheels from locking so you can still steer. On dry asphalt the distance is about the same; on gravel or snow it can even be slightly longer.
Q. What about going downhill?
It gets longer, because gravity pulls the car along. A 10% grade behaves roughly like losing 0.1 of grip.
Q. Why are school zones 30 km/h?
The table shows it plainly: 50 km/h and 30 km/h are only 20 km/h apart, yet the dry stopping distances are 26 m and 13 m — twice as far.