Braking Distance Calculator
Stopping distance split into reaction distance and braking distance, plus the total time.
Results
Total stopping distance
70.52
m
Braking distance
45.52
m
Distance during reaction
25.00
m
Time
4.64
s
What this tool does
Braking distance grows with the square of the speed, so going from 50 to 90 km/h more than triples it while the reaction distance only rises in proportion. A friction coefficient of 0.7 represents dry asphalt; wet roads are nearer 0.4 and ice below 0.15.
Formula
d = v·t_reaction + v² ÷ (2·µ·g)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
v | Speed | km/h |
tr | Reaction time | s |
mu | Friction coefficient | — |
D | Total stopping distance | m |
B | Braking distance | m |
R | Distance during reaction | m |
T | Time | s |
Worked example
- Speed90 km/h
- Reaction time1 s
- Friction coefficient0.7
- Total stopping distance70.52 m
- Braking distance45.52 m
- Distance during reaction25.00 m
- Time4.64 s
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.