Blood Alcohol Content Estimator

Estimate your blood alcohol concentration (BAC) based on drinks consumed, body weight, sex, and time elapsed.

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1. Select your sex (male or female) for the correct Widmark body water ratio. 2. Enter your body weight in kilograms or pounds. 3. Enter the number and type of standard drinks consumed (beer, wine, or spirits). 4. Enter the hours elapsed since your first drink. 5. View your estimated BAC, impairment level, legal driving status, and time until sober.

About This Tool

Understanding your approximate blood alcohol concentration (BAC) can help you make more informed decisions about alcohol consumption and driving safety. Our BAC Estimator uses the Widmark formula, the most widely accepted method for estimating blood alcohol levels, factoring in the number of standard drinks, your body weight, sex, and the time elapsed since drinking.

The calculator shows your estimated BAC level along with typical effects at that concentration, legal driving limits for various countries, and the estimated time until your BAC returns to zero. It also explains what constitutes a standard drink across different beverage types - beer, wine, and spirits.

This tool provides estimates only and should never be used as the sole basis for deciding whether to drive. Actual BAC varies based on food intake, medications, metabolism, hydration, liver function, and individual tolerance. When in doubt, do not drive. Use a designated driver, rideshare service, or public transportation.

Formula / How It Works

Widmark formula: BAC = (alcohol in grams / (body weight in grams x r)) - (0.015 x hours). r = 0.68 for men, 0.55 for women. Standard drink = 14g pure alcohol.

Frequently Asked Questions

In the United States, the legal limit is 0.08% for drivers aged 21 and over. Many countries have lower limits - 0.05% in Australia, Germany, and France, and 0.00% in some countries. Commercial drivers in the US have a 0.04% limit. Check your local laws.
BAC is estimated using the Widmark formula: BAC = (alcohol consumed in grams / (body weight in grams x r)) - (0.015 x hours since drinking). The "r" factor is 0.68 for men and 0.55 for women, reflecting differences in body water content.
In the US, a standard drink contains about 14 grams of pure alcohol. This equals approximately 12 oz (355 mL) of regular beer at 5%, 5 oz (148 mL) of wine at 12%, or 1.5 oz (44 mL) of distilled spirits at 40%. Other countries define standard drinks differently.
Your body metabolizes alcohol at a roughly constant rate of about 0.015% BAC per hour (approximately one standard drink per hour). There is no way to speed this up - coffee, food, water, and exercise do not reduce BAC faster.
Women generally have a higher BAC than men after consuming the same amount of alcohol due to lower body water percentage (55% vs 68%), typically lower body weight, and differences in stomach enzyme activity that affects alcohol metabolism.

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