Stopping Distance Calculator (Reaction + Braking)
Stopping Distance Calculator (Reaction + Braking)
Real-world stopping distance has two parts: the reaction distance covered before the brakes are even applied, and the braking distance covered while decelerating. Enter the initial speed, braking deceleration, and reaction time, and this calculator computes all three distances.
Reaction distance is simply speed multiplied by reaction time, since the vehicle keeps moving at a constant speed for that entire interval before braking even begins — a detail that's easy to forget when only thinking about braking performance. Both components grow with speed, but braking distance grows much faster: since it depends on speed squared (via the SUVAT relationship v² = u² − 2as with final velocity zero), doubling your speed doesn't just double the braking distance, it roughly quadruples it — a genuinely important safety fact this calculator makes concrete rather than abstract.
- Reaction distance = speed × reaction time, since the vehicle keeps moving at constant speed during the driver's reaction time before braking starts.
- Braking distance = u² / 2a, using the SUVAT third equation with final velocity zero, where a is the deceleration.
- Both distances grow with speed, but braking distance grows with the square of speed - doubling your speed roughly quadruples the braking distance, which is why speed limits matter so much for safety.
How do I calculate total stopping distance?
Add the reaction distance (speed × reaction time) to the braking distance (speed² ÷ (2 × deceleration)).
What is the stopping distance at 20 m/s with a 1.5 s reaction time and 5 m/s² of braking?
Reaction distance = 20 × 1.5 = 30 m. Braking distance = 20² / (2×5) = 40 m. Total = 70 m.
Stopping Distance Calculator (Reaction + Braking)
Real-world stopping distance has two parts: the reaction distance covered before the brakes are even applied, and the braking distance covered while decelerating. Enter the initial speed, braking deceleration, and reaction time, and this calculator computes all three distances.
Reaction distance is simply speed multiplied by reaction time, since the vehicle keeps moving at a constant speed for that entire interval before braking even begins — a detail that's easy to forget when only thinking about braking performance. Both components grow with speed, but braking distance grows much faster: since it depends on speed squared (via the SUVAT relationship v² = u² − 2as with final velocity zero), doubling your speed doesn't just double the braking distance, it roughly quadruples it — a genuinely important safety fact this calculator makes concrete rather than abstract.
- Reaction distance = speed × reaction time, since the vehicle keeps moving at constant speed during the driver's reaction time before braking starts.
- Braking distance = u² / 2a, using the SUVAT third equation with final velocity zero, where a is the deceleration.
- Both distances grow with speed, but braking distance grows with the square of speed - doubling your speed roughly quadruples the braking distance, which is why speed limits matter so much for safety.
How do I calculate total stopping distance?
Add the reaction distance (speed × reaction time) to the braking distance (speed² ÷ (2 × deceleration)).
What is the stopping distance at 20 m/s with a 1.5 s reaction time and 5 m/s² of braking?
Reaction distance = 20 × 1.5 = 30 m. Braking distance = 20² / (2×5) = 40 m. Total = 70 m.