How Long Does Alcohol Stay in Your System?
Blood alcohol concentration (BAC) depends on how much you drink, your body weight, and your sex. This calculator uses the Widmark formula to estimate your peak BAC and how long it takes to reach zero or fall below the legal driving limit. The body metabolizes alcohol at roughly 0.015% per hour on average, regardless of coffee, food, or exercise after drinking.
In the United States, the legal BAC limit for driving is 0.08% for adults 21 and over. However, any level of alcohol can impair judgment and reaction time. This calculator provides estimates only. Always use a designated driver, rideshare, or public transit after drinking.
Frequently Asked Questions
The US federal legal limit for driving is 0.08% BAC for adults 21+. Some states have lower limits for commercial drivers (0.04%) or zero tolerance for under-21 drivers.
No. Coffee, water, food, or exercise cannot significantly speed up your liver's alcohol processing rate of ~0.015%/hour. Only time reduces BAC.
Women typically have lower body water percentage, meaning alcohol is more concentrated. The Widmark factor (r) is 0.68 for men and 0.55 for women, reflecting this difference.