Estimate total stopping distance including driver reaction time.
Before the brakes engage, the car travels at its original speed for the reaction time. Braking distance then scales with the square of speed divided by grip. Because speed enters squared, a small speed rise produces a much longer stop, which is the core physics argument for slower driving.
Stopping Distance
Total = v x reaction time + v^2 / (2 x friction x 32.174)
Total = v x reaction time + v^2 / (2 x friction x 32.174) Before the brakes engage, the car travels at its original speed for the reaction time. Braking distance then scales with the square of speed divided by grip.
Because speed enters squared, a small speed rise produces a much longer stop, which is the core physics argument for slower driving.
This calculator takes 3 inputs: Speed, Reaction time, Tire friction. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.