Alcohol Effect on Reaction Time | The Real Millisecond Numbers
Even one drink measurably slows reaction time. At 0.05% BAC, reaction time slows by 30–50 ms; at 0.08%, by 80–120 ms — enough to add 2+ meters of braking distance at urban speed.
What Studies Actually Show
Meta-analyses (Moskowitz & Fiorentino) consistently find dose-dependent reaction-time impairment starting at 0.02% BAC. Variance and lapse rate climb even faster than mean reaction time.
Do Not Use This to Decide to Drive
A reaction test cannot certify you sober. Even when reaction time looks "normal", judgment, attention and lapse rate are impaired. This page is educational, not legal advice.
See your sober baseline
FAQ
Can I use this to test if I am sober enough to drive?
No. Use a breathalyzer and the law in your country. Reaction tests cannot certify sobriety.
How much does one drink slow reaction time?
Typically 20–40 ms at 0.02–0.05% BAC, with much larger lapse-rate increases.
Is the test free?
Yes, fully free, no signup.