How Alcohol Is Broken Down, and How Long It Takes
After a drink, alcohol is absorbed in the stomach and small intestine, then metabolized primarily in the liver by alcohol dehydrogenase (ADH). This metabolic rate is fairly constant, which is why blood alcohol concentration (BAC) declines in a nearly linear fashion over time — on average, about 0.015% per hour. This calculator uses that average elimination rate to estimate how long full detox will take.
Estimating Peak BAC with the Widmark Formula
The calculation is based on the widely used Widmark formula. Pure alcohol consumed (volume × ABV × 0.8) is divided by body weight and a sex-specific body water distribution constant (0.68 for men, 0.55 for women) to estimate peak BAC, which is then divided by the elimination rate to find when BAC returns to zero. Reduced liver health is factored in as a slower elimination rate.
Reference Only — Individual Variation Matters
Actual alcohol metabolism speed varies widely based on genetic enzyme activity, whether you ate beforehand, medications, and sleep status. The calculated time assumes average conditions and is a reference estimate only. If you feel any lingering effects at all, never drive — wait until you've fully recovered before resuming normal activity.
Frequently Asked Questions
On average, blood alcohol concentration drops by about 0.015% per hour. With reduced liver function, it may clear more slowly, around 0.010% per hour.
The estimate is based on an average elimination rate. Individual variation is significant, so build in extra buffer time and never drive if you still feel any effects.
Water helps with dehydration and hangover symptoms, but it doesn't meaningfully speed up the liver's actual rate of alcohol metabolism.