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

Name: Blood Alcohol Content Calculator
Availability: InStock
Author: Nham Vu

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