BAC Calculator
Map alcohol intake to blood concentration using the Widmark formula. Quantify metabolic decay rates and estimate time to 0% with gender-specific factors.
Please configure parameters and execute the action.
About BAC Calculator
BAC Calculator uses a Widmark-style estimate to turn body weight, elapsed time, and drink strength into an approximate blood alcohol concentration. It also shows the amount of pure alcohol consumed, the approximate number of standard drinks, and an estimated time until the level returns to 0%.
How To Use It
Enter body weight and elapsed time first, then add the drinks consumed so far.
- Choose male or female and enter body weight in pounds.
- Set the hours and minutes since the first drink, then add one or more drink rows with amount, size, and ABV.
- Click Calculate BAC to review the estimated concentration and recovery time.
Examples
-
Two light beers
Input: Gender: Male Body Weight: 176.4 lb Time Since First Drink: 1 hour 30 minutes Drink 1: 2 x 12 oz at 5% ABV Output: Estimated BAC: 0.025% Status: Low Time Until 0%: 1.7 hours
-
Wine and spirits mix
Input: Gender: Female Body Weight: 145 lb Time Since First Drink: 2 hours Drink 1: 1 x 5 oz at 12% ABV Drink 2: 1 x 1.5 oz at 40% ABV Output: Estimated BAC: 0.034% Status: Caution Time Until 0%: 2.3 hours
Real-World Usage Scenarios
- Planning Recovery Time - If you need to be alert the following morning, use the tool to estimate the time until your concentration returns to 0%. By entering your planned consumption and weight, you can see if the standard elimination rate of 0.015% per hour allows for a full recovery before your commute.
- Educational Metabolism Comparisons - Understand how biological factors influence alcohol processing. Compare how a 180 lb male and a 140 lb female process the same amount of alcohol. This helps illustrate why identical drink counts result in significantly different levels of impairment based on body water ratios.
- Monitoring Cumulative Intake - Track a long evening involving different types of drinks, such as a high-ABV craft beer followed by a standard glass of wine. The tool aggregates the total pure alcohol consumed to provide a single, unified estimate of your current status rather than relying on a simple drink count.
Frequently Asked Questions
How accurate is the Widmark formula calculation?
It provides a mathematical estimate based on averages. Individual variables such as recent food intake, metabolic health, and hydration are not factored in. It should be used for educational purposes and never to determine if it is safe to operate machinery.
Does eating food before drinking change the result?
Food in the stomach slows the absorption of alcohol into the bloodstream but does not change the total amount of alcohol your liver must eventually process. This calculator assumes full absorption to provide a conservative estimate of your peak concentration.
Why does the tool require a gender selection?
Biological males and females typically have different body water percentages. Alcohol is water-soluble; since males generally have a higher water-to-fat ratio, the alcohol is more diluted, resulting in a lower concentration for the same body weight.
