Blood Alcohol Content (BAC) Calculator
Warning: This calculator provides estimates only. Many factors affect BAC including food intake, medications, and individual metabolism. Never drink and drive.
What is a Standard Drink?
In the US, a standard drink contains about 14 grams (0.6 oz) of pure alcohol:
Important Warning
This calculator provides estimates only. Actual BAC varies based on many factors. Never drink and drive. If you've been drinking, use a designated driver, taxi, or rideshare service.
Legal Limits (US)
Related Calculators
Understanding Blood Alcohol Content
What is BAC?
Blood Alcohol Content (BAC) is the percentage of alcohol in your bloodstream. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. It's the standard measure used to determine legal intoxication levels.
The Widmark Formula
Where r = 0.68 for men and 0.55 for women (water distribution ratios)
BAC Levels and Effects
| BAC Level | Typical Effects |
|---|---|
| 0.02-0.03% | Slight mood elevation, relaxation, minor impairment |
| 0.04-0.06% | Lowered inhibitions, euphoria, minor reasoning impairment |
| 0.07-0.09% | Slight impairment of balance, speech, vision, reaction time |
| 0.10-0.12% | Significant impairment of motor coordination, judgment |
| 0.13-0.15% | Gross motor impairment, blurred vision, anxiety, restlessness |
| 0.16-0.20% | Nausea, disorientation, emotional instability |
| 0.25%+ | Severe impairment, risk of alcohol poisoning, loss of consciousness |
Factors Affecting BAC
Body Weight
Heavier people have more body water to dilute alcohol, resulting in lower BAC.
Gender
Women typically have higher BAC from the same drinks due to lower body water percentage.
Food Intake
Food slows alcohol absorption. Drinking on an empty stomach raises BAC faster.
Drinking Speed
The faster you drink, the higher your peak BAC. Spacing drinks allows metabolism to keep up.
Alcohol Metabolism
Your body processes alcohol at a relatively constant rate:
This is roughly one standard drink per hour. Coffee, cold showers, and exercise do NOT speed up alcohol metabolism—only time does.
What is a Standard Drink?
In the United States, a standard drink contains about 14 grams (0.6 fluid ounces) of pure alcohol. This is typically found in:
Driving and BAC
Impairment Begins Before Legal Limits
Driving ability is impaired well before reaching the legal limit. At just 0.02% BAC, decline in visual functions and ability to perform two tasks at the same time begins. The safest choice is to not drive after drinking any amount of alcohol.
Disclaimer
This calculator provides rough estimates for educational purposes only. Individual metabolism varies significantly based on genetics, medications, health conditions, and other factors. Never rely on a calculator to determine if you're safe to drive. When in doubt, don't drive.
Frequently Asked Questions
What BAC level is considered legally drunk?
In the United States, the legal limit for drivers 21 and over is 0.08% BAC. Commercial drivers face a stricter limit of 0.04%, and those under 21 have zero-tolerance policies (0.00-0.02% depending on state). However, impairment begins well before these limits - even 0.02% BAC affects visual function and multitasking ability.
How long does it take for alcohol to leave your system?
The body metabolizes alcohol at a constant rate of approximately 0.015% BAC per hour, regardless of how much you've consumed. This equals roughly one standard drink per hour. Nothing speeds up this process - not coffee, cold showers, exercise, or food. Only time reduces BAC.
Why do women typically reach higher BAC levels than men?
Women generally reach higher BAC levels than men when consuming the same amount of alcohol due to several factors: lower body water percentage (alcohol dilutes in body water), typically lower body weight, and differences in alcohol-metabolizing enzymes. Hormonal fluctuations can also affect alcohol metabolism.
What is a standard drink?
In the US, a standard drink contains about 14 grams (0.6 oz) of pure alcohol. This equals approximately 12 oz of regular beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV). Many cocktails and craft beers contain more alcohol than one standard drink.