Alcohol Calculator
Estimate your blood alcohol concentration (BAC) using the Widmark formula. Enter your drinks, body weight, and time elapsed to see your estimated BAC level and time until sober.
BAC Estimator
Total servings consumed
Your body weight in pounds
Affects body water ratio used in the Widmark formula
How to Use This Tool
Enter Your Drinks
Select the type of drink and enter how many servings you have consumed
Add Your Details
Enter your body weight and biological sex, then adjust the time since your first drink
View Your BAC
See your estimated blood alcohol concentration, impairment level, and time until sober
Widmark Formula
BAC = (A / (W * r)) * 100 - (0.015 * t)The Widmark formula estimates BAC using these variables:
- A = total alcohol consumed in grams (standard drinks x 14g)
- W = body weight in grams
- r = Widmark factor (0.68 for males, 0.55 for females)
- t = time in hours since first drink
- 0.015 = average metabolic elimination rate (BAC per hour)
The Widmark factor accounts for differences in body water distribution between biological sexes. Males typically have a higher water-to-body-weight ratio, which dilutes alcohol more effectively.
The metabolic rate of 0.015% per hour is an average. Individual rates vary from about 0.010% to 0.020% per hour depending on liver function, genetics, and other factors.
Frequently Asked Questions
How accurate is this BAC calculator?
This calculator uses the Widmark formula, which is the standard method for estimating BAC. However, actual BAC varies based on many factors including food intake, medication, liver health, and individual metabolism. This is an estimate for educational purposes only and should not be used to determine fitness to drive.
What is a standard drink?
In the United States, a standard drink contains about 14 grams of pure alcohol. This equals approximately 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV).
What is the legal BAC limit for driving?
In most US states, the legal BAC limit for driving is 0.08%. However, impairment begins at much lower levels. Many countries have lower limits (e.g., 0.05% in Australia, 0.02% in Sweden). Even below the legal limit, alcohol affects reaction time and judgment.
How long does it take for alcohol to leave your system?
On average, your body metabolizes alcohol at a rate of about 0.015% BAC per hour. This means one standard drink takes roughly 1 to 1.5 hours to metabolize. Factors like body weight, liver health, food intake, and hydration can affect this rate.
Published by Kalcify · Last updated
Calculators are built against primary sources — government tax authorities (IRS, HMRC, CRA, ATO) for finance and the World Health Organization for health metrics. Updated when rates or rules change. View methodology and data sources.
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