Frequently asked questions
Can I use this calculator to decide if I'm safe to drive?
Absolutely not. This is a rough mathematical estimate that cannot account for individual metabolism, food intake, hydration, fatigue, medications, or liver function. Real BAC varies significantly between individuals with the same inputs. If you have had any alcohol, the only safe choice is not to drive.
What is a standard drink?
A standard drink contains 14 grams (0.6 oz) of pure alcohol. This equals approximately one 12 oz (355 mL) beer at 5%, one 5 oz (150 mL) glass of wine at 12%, or one 1.5 oz (44 mL) shot of spirits at 40%. Craft beers, large pours, and strong cocktails often contain more than one standard drink.
Why does body weight affect BAC?
Alcohol distributes through body water. A heavier person has more water volume to dilute the alcohol, resulting in a lower concentration (BAC) from the same amount consumed. This is also why women typically reach higher BAC from the same intake, as they have proportionally less body water.
How fast does the body metabolize alcohol?
The average person eliminates alcohol at about 0.015% BAC per hour (roughly one standard drink per hour for a 70 kg person). This rate is fairly constant regardless of how much you drink. Coffee, cold showers, and food do not speed up elimination; only time reduces BAC.
Why does food affect how drunk I feel?
Food slows alcohol absorption from the stomach, leading to a lower peak BAC and a more gradual rise. It does not reduce total alcohol absorbed, just the rate. Drinking on an empty stomach can produce peak BAC 50% higher than the same drinks consumed with a full meal.
What BAC is the legal limit for driving?
Legal limits vary by jurisdiction: 0.08% in the US, UK, and Canada; 0.05% in Australia, most of Europe, and many other countries; 0.00% in some countries (Czech Republic, Hungary, Romania). Commercial drivers often face stricter limits (0.04% in the US). These are the per se limits; impairment charges can apply at any BAC.