⚠️ Important Disclaimer: This calculator provides estimates only. Actual BAC varies based on food intake, metabolism, medications, hydration, and other factors. Never drink and drive. Legal BAC limits vary by jurisdiction (typically 0.08% in the US). This tool is for educational purposes only.

About This Calculator

The BAC Calculator estimates your Blood Alcohol Concentration using the Widmark formula, a scientifically validated method developed by Swedish professor Erik Widmark in the 1930s. This formula accounts for body weight, biological sex (which affects body water content), number of standard drinks consumed, and time elapsed since drinking began.

How to Use

Select your biological sex (affects alcohol distribution)
Choose your preferred weight unit (kg or lb)
Enter your body weight
Enter the number of standard drinks consumed
Enter hours since your first drink
Click Calculate to see your estimated BAC

📚 Understanding Blood Alcohol Concentration

Blood Alcohol Concentration (BAC) measures the amount of alcohol in your bloodstream, expressed as a percentage. For example, a BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood.

BAC is influenced by several factors including body weight, biological sex (women typically have higher BAC due to lower body water content), rate of consumption, food in stomach, tolerance, and individual metabolism.

The liver metabolizes alcohol at an average rate of about 0.015% BAC per hour, though this can vary between 0.010% and 0.020% depending on the individual.

🧮 Widmark Formula

The Widmark formula calculates BAC as follows:


              BAC = (A × 5.14 / W × r) − 0.015 × H

Where:

A = Total alcohol consumed in ounces
W = Body weight in pounds
r = Alcohol distribution ratio (0.73 for men, 0.66 for women)
H = Hours since first drink
0.015 = Average alcohol elimination rate per hour

Example: A 154 lb male who consumed 3 standard drinks over 2 hours:
BAC = (3 × 0.6 × 5.14 / 154 × 0.73) − 0.015 × 2 = 0.052%

📊 BAC Levels & Effects

BAC Level	Effects	Impairment
0.00–0.03%	Normal behavior, slight mood elevation	No impairment
0.03–0.06%	Mild euphoria, relaxation, lowered inhibitions	Slight impairment
0.06–0.10%	Reduced coordination, impaired judgment	Significant impairment
0.10–0.20%	Slurred speech, poor balance, nausea	Severe impairment
0.20–0.30%	Confusion, disorientation, possible blackout	Dangerous
>0.30%	Loss of consciousness, risk of death	Life-threatening

🍺 What is a Standard Drink?

A standard drink contains approximately 14 grams (0.6 oz) of pure alcohol:

Beer: 12 oz (355 mL) of regular beer (~5% alcohol)
Wine: 5 oz (148 mL) of wine (~12% alcohol)
Spirits: 1.5 oz (44 mL) of distilled spirits (~40% alcohol)
Malt liquor: 8 oz (237 mL) of malt liquor (~7% alcohol)

Note: Many drinks contain more than one standard drink. A 16 oz craft beer at 8% ABV contains about 2 standard drinks.

💡 Practical Use Cases

Personal Awareness: Understand how alcohol affects your body
Safety Planning: Estimate when it may be safe to drive (always err on caution)
Education: Learn about alcohol metabolism and its effects
Health Monitoring: Track drinking patterns and their impact
Medical Reference: Healthcare providers assessing alcohol-related conditions
Research: Understanding pharmacokinetics of alcohol

❓ Frequently Asked Questions

How accurate is this BAC calculator?

This calculator provides estimates based on the Widmark formula, which is scientifically validated but cannot account for individual variations. Actual BAC can vary by 20-30% based on factors like food intake, hydration, medications, and individual metabolism. Always use breathalyzer tests for accurate readings.

Why does biological sex affect BAC?

Women typically have a higher BAC than men after consuming the same amount of alcohol due to differences in body composition. Women generally have a higher percentage of body fat and lower percentage of body water, leading to higher alcohol concentration in the blood.

How long does it take to sober up?

The liver eliminates alcohol at an average rate of 0.015% BAC per hour. Nothing speeds up this process—not coffee, food, water, or exercise. Only time reduces BAC. For example, if your BAC is 0.08%, it takes approximately 5-6 hours to reach 0.00%.

What is the legal BAC limit for driving?

In the United States, the legal limit is 0.08% for drivers 21 and older (lower for commercial drivers and those under 21). Many countries have lower limits (0.05% or even 0.00%). Even below legal limits, alcohol impairs driving ability.

Does eating food affect BAC?

Yes, eating before or while drinking slows alcohol absorption, resulting in a lower peak BAC. However, food doesn't reduce the total amount of alcohol absorbed—it only delays absorption. The total alcohol will still be processed by your liver.