Why reaction time matters
Whenever you need to respond to something — a hazard on the road, a signal in a game, or a warning sound — there is a delay between noticing it and actually acting. During that delay, a moving object (like a car) keeps traveling at its original speed before any braking or correction begins.
How this calculator works
The calculator converts your speed to meters per second and multiplies it by your reaction time to get the distance covered before any braking starts (distance = speed x time). It then uses the standard kinematic braking formula, distance = speed² / (2 x deceleration), to estimate how far it takes to stop once braking begins. Adding the two gives the total stopping distance — the number that matters most for safe following distances.
Typical human reaction times for driving are often cited around 1.5 seconds including perception and movement, though this varies by person, alertness, and conditions. This tool is for general physics education and safety awareness, not a substitute for defensive driving training or official guidance.