Blood Alcohol Content Calculator – Estimate Your BAC Level

Use our BAC calculator to estimate your blood alcohol content based on the number of drinks, your body weight, and time elapsed. Stay safe and make informed decisions.

Gender

Weight

Unit

Number of Standard Drinks

1 drink = 12oz beer, 5oz wine, or 1.5oz spirits

Hours Since First Drink

How to Use This BAC Calculator

Enter your gender and weight

Select your gender and input your body weight. These affect how alcohol distributes in your body.

Input drinks and time elapsed

Enter the number of standard drinks consumed and hours since your first drink.

View your estimated BAC level

Get your blood alcohol content estimate along with impairment level information.

BAC Levels and Impairment Effects

BAC Range	Impairment Level	Effects
0.00%	Sober	No impairment
0.01-0.02%	Minimal	Relaxation, slight mood change
0.03-0.05%	Mild	Reduced inhibition, impaired judgment
0.06-0.07%	Impaired	Reduced coordination, slower reaction time
0.08-0.10%	Legally Intoxicated	Poor muscle coordination, impaired balance and speech
0.11-0.15%	Highly Impaired	Significant motor impairment, slurred speech
0.16-0.20%	Severely Impaired	Nausea, vomiting, dysphoria
0.25%+	Dangerous	Risk of alcohol poisoning, loss of consciousness

Understanding Blood Alcohol Content

What Is BAC?

Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream. A BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood. This is the legal limit for driving in most U.S. states, though impairment begins at much lower levels.

How the Widmark Formula Works

This calculator uses the Widmark formula, developed in the 1930s. It accounts for total alcohol consumed, body weight, gender (which affects water content), and time for metabolism. The formula estimates peak BAC, then subtracts alcohol metabolized over time at approximately 0.015% per hour.

Why Gender Matters

Women typically have higher BAC than men after drinking the same amount. This is because women have less body water (about 55% vs 68% in men) and lower levels of alcohol dehydrogenase, the enzyme that breaks down alcohol in the stomach.

Tips for Responsible Drinking

Never drink and drive

Even one drink can impair driving. Plan a ride home before you start drinking.

Pace yourself

Limit yourself to one standard drink per hour. Your liver can only process about one drink per hour.

Eat before and during drinking

Food slows alcohol absorption. Avoid drinking on an empty stomach.

Know what counts as a standard drink

12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%) each contain about 14g of pure alcohol.

Frequently Asked Questions

How accurate is this BAC calculator?

This calculator provides an estimate based on the Widmark formula. Actual BAC varies based on genetics, metabolism, food intake, medication, and other factors. Never rely on calculator results to determine if you are safe to drive.

How long does it take to sober up?

Your body metabolizes alcohol at about 0.015% BAC per hour. If your BAC is 0.08%, it takes roughly 5-6 hours to reach zero. Coffee, cold showers, and exercise do not speed up this process — only time works.

Can I be under the limit but still impaired?

Yes. Impairment begins with the first drink. Studies show reduced reaction time and judgment at 0.02% BAC. The legal limit is not a safety threshold — it is a legal definition for prosecution.

What affects how quickly I get drunk?

Body weight, gender, food intake, drinking speed, medication, fatigue, and genetics all affect BAC. Carbonated drinks may increase absorption rate. Drinking on an empty stomach leads to faster and higher peak BAC.

Is the legal BAC limit the same everywhere?

No. Most U.S. states use 0.08% for regular drivers, but commercial drivers face a 0.04% limit. Some countries have lower limits (0.05% in much of Europe, 0.02% in parts of Asia). For drivers under 21, most U.S. states have zero tolerance laws (0.01-0.02%).

Other Free Tools

Search tools