Average Human Reaction Time Calculator

Average human reaction time

Human reaction time is the gap between a stimulus and the voluntary motor response it triggers. On a simple reaction task, baseline figures usually land around 200 to 250 ms for visual stimuli, 150 to 200 ms for auditory, and 100 to 150 ms for tactile. Touch wins because it reaches the motor cortex by the shortest neural route.

When there are several stimuli mapped to different responses, choice reaction times follow Hick's Law: RT = a + b · log₂(n + 1), so the more options you have, the longer it takes. Plenty of things drag reaction down. Age does it (roughly 10 ms slower per decade after 25), as do fatigue, alcohol (about 30 to 100 ms slower per 0.05% BAC) and distraction. Training, caffeine and plain attention push it back the other way.

Applications

It shows up in ergonomics (HMI design, control-room layouts), in sports (sprint starts, goalkeeping), in aviation (pilot response budgets) and in vehicle safety. When working out stopping sight distance, the Brazilian CONTRAN and most highway engineering manuals assume 1.5 s of perception-reaction time, enough to cover recognition, the decision itself, and motor activation.

FAQ

Why is the driving figure (1.5 s) so much higher than 250 ms? The lab number captures only the motor response to a stimulus you're already expecting. Behind the wheel you also have to perceive something, recognise it (Is that a pedestrian?), choose what to do (brake or swerve?), and then get your foot onto the pedal.

Does texting really slow reaction that much? It does. Studies put the increase at 35 to 40%, which is roughly what you'd see at a BAC of 0.08%, the legal limit in many countries.

What is the absolute minimum possible? Around 100 ms. In athletics, anything quicker counts as a false start, since it's below what conscious sensorimotor processing can actually manage.