Cars & Vehicles
Braking distance calculator
Reaction + braking distance from speed and road condition.
- Instant
- Free
- Private (processed locally)
- No sign-up
Calculate stopping distance
Enter the speed, the reaction time and the road condition: the tool gives reaction, braking and total distance.
Grip (µ) by road
- Dry: µ ≈ 0.8
- Wet: µ ≈ 0.4
- Snow: µ ≈ 0.2
- Ice: µ ≈ 0.1
Example
| Input | Value |
|---|---|
| Speed | 90 km/h |
| Reaction | 1 s |
| Road | Dry |
| Reaction distance | 25 m |
| Braking distance | ≈ 39.8 m |
| Stopping distance | ≈ 64.8 m |
Indicative model. 100% local calculation.
Frequently asked questions
Which formula is used?
Reaction = speed × reaction time; braking = v² / (2·µ·g), with g = 9.81 m/s² and µ the grip coefficient.
Why does distance grow so fast with speed?
Braking depends on the square of speed: doubling speed quadruples the braking distance.
What reaction time should I use?
About 1 s for an alert driver; more with fatigue, distraction or alcohol.