Blood Alcohol Content (BAC) Estimator
Use this calculator to get an estimated Blood Alcohol Content (BAC) level based on your consumption. Please remember this is an estimation and should not be used to determine fitness to drive or operate machinery. Individual factors can vary widely.
Male
Female
e.g., 12 for a beer, 5 for wine, 1.5 for a shot
e.g., 5 for beer, 12 for wine, 40 for spirits
Understanding Blood Alcohol Content (BAC)
Blood Alcohol Content (BAC) is a measure of the amount of alcohol in your blood, expressed as a percentage. For example, a BAC of 0.10% means that there are 0.10 grams of alcohol for every 100 milliliters of blood. BAC is a critical indicator of intoxication and is used legally to define impairment for activities like driving.
How BAC is Calculated (Widmark Formula)
The calculator above uses a simplified version of the Widmark formula, a widely accepted method for estimating BAC. The core idea is to determine the total amount of pure alcohol consumed and then distribute it across the body's water content. Key factors include:
- Total Alcohol Consumed: This depends on the number of drinks, their volume, and their alcohol percentage. Pure alcohol has a density of approximately 0.789 g/ml.
- Body Weight: Heavier individuals generally have more body water, which dilutes the alcohol more effectively, leading to a lower BAC for the same amount of alcohol consumed.
- Gender: Women typically have a higher percentage of body fat and less body water than men of the same weight. This means alcohol is less diluted in women's bodies, often resulting in a higher BAC. The 'Widmark factor' (r) accounts for this difference (approximately 0.70 for men and 0.58 for women).
- Time Elapsed: The liver metabolizes alcohol at a relatively constant rate, typically around 0.015% BAC per hour. The calculator subtracts this metabolized alcohol from the peak BAC.
Factors Affecting BAC (Beyond the Calculator)
While this calculator provides a useful estimate, many other factors can influence your actual BAC:
- Food Consumption: Eating before or while drinking slows the absorption of alcohol into the bloodstream, leading to a lower peak BAC.
- Medications: Certain medications can interact with alcohol, intensifying its effects or altering its metabolism.
- Hydration Level: Dehydration can lead to a higher BAC.
- Genetics: Individual genetic variations can affect how quickly alcohol is metabolized.
- Fatigue: Being tired can amplify the effects of alcohol.
- Rate of Consumption: Drinking quickly leads to a higher peak BAC than sipping drinks over a longer period.
BAC Levels and Their Effects (General Guidelines)
- 0.02% – 0.03%: Mild relaxation, slight body warmth, altered mood.
- 0.05% – 0.06%: Impaired judgment, lowered inhibitions, exaggerated behavior, reduced coordination. This is the legal limit for driving in many countries.
- 0.08%: Legal intoxication limit in most of the U.S. Significant impairment of motor skills, speech, and balance.
- 0.10% – 0.12%: Clear deterioration of reaction time and control, slurred speech, poor coordination.
- 0.15%: Gross impairment of physical control, blurred vision, significant loss of balance.
- 0.20% – 0.29%: Nausea, vomiting, severe motor impairment, memory blackouts.
- 0.30% – 0.39%: Loss of consciousness, potential for respiratory depression.
- 0.40% and above: Risk of coma, severe respiratory depression, and death.
Disclaimer: This calculator provides an estimate only and should not be used to make decisions about driving, operating machinery, or any other activity requiring sobriety. Always drink responsibly and never drink and drive. If you are concerned about your alcohol consumption, please seek professional help.