🍺BAC Calculator

Estimate blood alcohol content based on drinks, weight, and time.

Number of Drinks

Drink Type

Weight (kg)

Gender

Hours Since First Drink

About BAC Calculator

This BAC calculator uses the Widmark formula to estimate blood alcohol concentration based on the number of standard drinks consumed, your body weight, gender, and the time elapsed since your first drink. Because alcohol metabolism varies by individual, this tool provides an estimate for educational awareness — it should never be used to determine whether it is safe to drive. Legal impairment in most US states begins at 0.08% BAC.

How to Use BAC Calculator

1
Enter your details
Input your weight, gender, and the number of standard drinks consumed.
2
Add the time elapsed
Enter how many hours have passed since your first drink so the calculator can subtract metabolized alcohol.
3
Review the estimate
See your estimated BAC and compare it to legal thresholds — for awareness only, never to justify driving.

Common Use Cases

Understanding how many drinks raise BAC to the legal limit for your weight
Estimating when BAC returns to zero after an evening of drinking
Educational use in health classes or alcohol awareness programs
Making informed decisions about pacing drinks at a social event

Frequently Asked Questions

What counts as one standard drink?

In the US, one standard drink contains 14 grams of pure alcohol. That equals: 12 oz regular beer (5% ABV), 5 oz wine (12% ABV), or 1.5 oz distilled spirits (40% ABV). Many cocktails, craft beers, and large pours contain multiple standard drinks.

How long does it take for BAC to reach zero?

The body eliminates alcohol at a fairly constant rate of approximately 0.015% BAC per hour. At 0.08% BAC, it takes roughly 5–6 hours to return to zero. Coffee, food, cold showers, and water do not speed up this process — only time does.

Why does body weight affect BAC?

Alcohol distributes through body water. Larger people have more total body water, which dilutes alcohol more effectively and results in a lower BAC from the same number of drinks. Gender also matters because women generally have a lower body water percentage than men of the same weight, leading to higher BAC.