BAC Calculator
Estimate your blood alcohol content based on drinks, weight, and time.
This calculator provides estimates only. Actual BAC varies by individual. Never drive if you've been drinking — when in doubt, don't.
Beer
12 oz · 5% ABV
Wine
5 oz · 12% ABV
Spirit
1.5 oz · 40% ABV
What is BAC?
Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream. A BAC of 0.08% — the legal driving limit in most US states and Canadian provinces — means there are 0.08 grams of alcohol per 100 milliliters of blood. This calculator uses the Widmark formula to estimate BAC based on the number of standard drinks consumed, body weight, gender, and elapsed time. Results are estimates only — actual BAC depends on many individual factors including food intake, metabolism, medications, and tolerance.
How to Use
- Select your gender and enter your body weight.
- Add the drinks you've consumed using the counters (beer, wine, spirits).
- Enter how many hours have passed since your first drink.
- Review your estimated BAC and the projected time until sober.
Frequently Asked Questions
Why does gender affect BAC?
Women generally have a higher proportion of body fat and lower proportion of body water compared to men of the same weight. Since alcohol distributes through body water, women typically reach a higher BAC than men after consuming the same amount of alcohol. The Widmark body water constant is approximately 0.68 for men and 0.55 for women.
How fast does the body process alcohol?
The liver metabolizes alcohol at a roughly constant rate of about 0.015% BAC per hour (approximately one standard drink per hour). This rate doesn't speed up with coffee, food, water, or cold showers — those may help you feel more alert, but they don't lower your BAC faster. Only time reduces your blood alcohol level.
What counts as a standard drink?
In the US, one standard drink contains about 14 grams (0.6 oz) of pure alcohol. That's roughly: 12 oz of regular beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV). Be aware that many craft beers are 7–10% ABV, and a typical restaurant wine pour may be 6–8 oz, so actual consumption often exceeds these standard measures.
