🛑 Stopping Distance Calculator

Stopping distance is how far a vehicle travels from the moment a driver perceives a hazard until it comes to a complete stop. It has two parts.

Total Stopping Distance = Reaction Distance + Braking Distance

Reaction distance is how far the car travels during the driver's reaction time (before the brakes are applied): Reaction Distance = Speed × Reaction Time. Braking distance is how far it travels after the brakes engage, following:

Braking Distance = Speed² ÷ (2 × μ × 9.81)

Here μ (the friction coefficient) represents the grip between tires and road surface, and it varies significantly with road conditions.

Converting speed to meters per second: 100 ÷ 3.6 ≈ 27.78 m/s.

Reaction distance = 27.78 × 1.5 ≈ 41.7 m
Braking distance = 27.78² ÷ (2 × 0.7 × 9.81) ≈ 56.2 m
Total stopping distance ≈ 41.7 + 56.2 = about 97.9 m

In other words, driving at 100 km/h and reacting to a hazard requires nearly the length of a football pitch — about 98 m — before the car comes to a full stop.

This calculator provides an educational estimate. Actual stopping distance varies with tire wear, vehicle load, the presence of ABS or electronic braking assistance, and road slope (downhill or uphill).

The dry/wet/ice μ values are typical reference figures — actual friction depends on the specific road surface and tires involved. Always keep a safe following distance, and defer to your vehicle's manual and real road conditions for actual braking performance.