How accurate is this calculator?

This calculator uses the widely accepted Widmark formula, which provides a reasonable estimate. However, actual BAC depends on many factors including food intake, hydration, medication, genetics, and drinking speed. Treat results as rough estimates only.

What counts as one standard drink?

In the US, one standard drink contains roughly 14 g of pure alcohol: 12 oz of regular beer (5%), 5 oz of wine (12%), or 1.5 oz of distilled spirits (40%). This calculator uses that 14 g definition.

Why does biological sex matter?

The Widmark formula uses a distribution factor (r) that differs by sex: approximately 0.68 for males and 0.55 for females. This reflects differences in body water percentage and fat distribution, meaning the same amount of alcohol typically produces a higher BAC in females.

How fast does the body metabolize alcohol?

The liver eliminates alcohol at roughly 0.015 g/dL per hour on average, which equals about one standard drink per hour. This calculator uses that rate; actual elimination varies between 0.010 and 0.020 g/dL/hour depending on the individual.

Can I use this to decide if I am safe to drive?

No. This tool is for educational purposes only. Impairment begins below the legal limit, and individual tolerance varies widely. If you have been drinking, use a rideshare, designate a sober driver, or wait until fully sober.

What is the legal BAC limit for driving?

In the US, the legal limit is 0.08% for drivers 21 and older. Many other countries use 0.05% or lower. Commercial drivers and those under 21 face stricter limits. Check your local laws.

Blood Alcohol Content Calculator

Estimate your blood alcohol concentration (BAC) using the Widmark formula — enter your weight, sex, drinks, and time elapsed.

Your Details

Body Weight

Biological Sex

Male Female

Number of Standard Drinks

1 drink = 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%)

Hours Since First Drink

Estimated BAC

—

% blood alcohol content (g/dL)

For educational use only. BAC estimates are not a reliable guide to impairment or fitness to drive. Never operate a vehicle after drinking. Individual metabolism varies widely.

Summary

This BAC calculator uses the Widmark formula to estimate your blood alcohol concentration based on your body weight, biological sex, the number of standard drinks consumed, and time elapsed since you started drinking. Results are estimates only and should never be used to make decisions about driving or operating machinery. Individual metabolism varies significantly.

How it works

Enter your body weight and select your unit (lbs or kg).
Select your biological sex, which affects the Widmark distribution factor.
Enter the number of standard drinks consumed.
Set how many hours have passed since your first drink.
Click Calculate to see your estimated BAC and a plain-English status.
Review the disclaimer — never rely on BAC estimates to judge fitness to drive.

Use cases

Understand how many drinks raise BAC to the legal limit in your jurisdiction.
Estimate how long to wait before BAC returns to zero.
Educational tool for health or safety training programs.
Compare how weight and sex affect BAC for the same drink count.
Plan responsible drinking at events by tracking drinks over time.
Help bartenders or event staff explain BAC concepts to guests.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu