BAC Calculator — Blood Alcohol Content Estimator
Estimate your blood alcohol content (BAC) based on what you have consumed. This tool uses the Widmark formula to help you understand how drinks, body weight, gender, and time affect your BAC level.
Important Disclaimer
This tool provides rough estimates for educational purposes only. Actual BAC depends on many factors including metabolism, food intake, medications, and individual tolerance. Never drink and drive.
Estimated BAC
0.042%
You may feel slightly relaxed, but you're under the legal limit in most states.
Impairment Level
Mild impairment. Reduced inhibition, slight coordination issues.
Time Until Sober
2h 47m
Estimated time until BAC reaches 0.000%
Legal BAC Limits
0.08%
Standard limit in 49 states for drivers 21+
0.05%
Utah's stricter limit for all drivers
0.04%
Limit for commercial (CDL) drivers in all states
0.00-0.02%
Zero-tolerance limit for drivers under 21
How to Use This Calculator
Select your gender and enter your body weight. Then enter the number of standard drinks you have consumed and how many hours have passed since your first drink. The calculator uses the Widmark formula to estimate your current BAC.
A standard drink is defined as 12 oz of beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of liquor (40% ABV). Each contains roughly the same amount of alcohol — about 14 grams.
Why BAC Matters for Drivers
In all 50 states, the legal BAC limit for drivers 21 and over is 0.08%. For drivers under 21, most states enforce a zero-tolerance policy (0.00-0.02% BAC). For commercial drivers, the limit is 0.04%. Driving above the legal limit is a DUI/DWI offense.
Impaired driving questions appear on virtually every DMV written exam. You should know the legal BAC limits, penalties for DUI, and how alcohol affects driving ability. Even at BAC levels below 0.08%, your reaction time and judgment are already impaired.
Frequently Asked Questions
What is the legal BAC limit for driving?
In all 50 US states, the legal BAC limit is 0.08% for drivers 21 and over. For drivers under 21, most states have zero-tolerance laws (0.00-0.02%). Commercial vehicle drivers have a limit of 0.04%.
How long does it take for BAC to reach zero?
The body metabolizes alcohol at an average rate of about 0.015% BAC per hour. So a BAC of 0.08% would take roughly 5-6 hours to reach zero. This rate cannot be sped up by coffee, cold showers, or exercise.
Is BAC on the DMV test?
Yes. DMV written exams include questions about legal BAC limits, implied consent laws, DUI penalties, and how alcohol affects driving ability. This is one of the most commonly tested topics.
What counts as one standard drink?
One standard drink is 12 oz of regular beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV). Each contains approximately 14 grams of pure alcohol.
Preparing for your DMV written test? Start with our free practice tests