Stopping Distance Calculator

The Highway Code's stopping distances versus physics-based estimates

The UK Highway Code publishes fixed stopping distance figures at set speeds (for example, 96 ft / 29 m total at 50 mph on a dry road), based on an average 0.67-second reaction time and average braking performance. Modern cars with ABS and better tyres often brake somewhat shorter than the Highway Code's decades-old braking figures, but the Highway Code numbers remain the reference used in the UK driving theory test, so expect this physics-based calculator to give slightly different results depending on the friction and reaction time you select.

The "two-second rule" as a rough real-world check

UK driving instructors commonly teach the "two-second rule" for the gap to the car in front on a dry road (doubled to four seconds in wet conditions), as a simpler alternative to calculating exact stopping distances while driving. It is a rule of thumb, not a substitute for the more precise distances this calculator produces, but it is a useful sanity check at a glance.