Braking Distance Calculator
Enter a speed, a reaction time and a dry, wet or icy road. See reaction distance, braking distance, the total and the formula. An estimate, not a safety guarantee — real tyres and roads differ.
Frequently asked questions
Which friction values are used?
Dry 0.7, wet 0.4 and ice 0.1, with gravity at 9.81 m/s². These are textbook assumptions for comparison, not a measurement of your tyres or the road.
Can I rely on this number?
No. It is an estimate, not a safety guarantee. Tyre wear, brakes, load, slope and road surface all change real stopping distance. Keep a bigger gap than the result.
Why does doubling speed more than double the distance?
Braking distance grows with the square of speed. Twice the speed needs about four times the braking distance.