Health & Fitness
Blood Alcohol Content (BAC) Calculator
Calculate your estimated blood alcohol content (BAC) based on your weight, gender, drinks consumed, and time elapsed.
Reviewed by the calculator.uk.com Team · Last reviewed 24 July 2026 · Our methodology
Enter values to calculate your estimated BAC
Related to Blood Alcohol Content (BAC) Calculator
The Blood Alcohol Content (BAC) calculator uses the Widmark formula, a scientifically validated method for estimating blood alcohol concentration. This calculation takes into account several key factors that influence how alcohol affects your body, including your weight, gender, number of drinks consumed, alcohol content of drinks, and time elapsed since drinking.
Key Factors in BAC Calculation
The calculator considers body water content (which differs between males and females), alcohol metabolism rate, and the standard drink measurements. It accounts for the gradual elimination of alcohol from your bloodstream over time, which occurs at an average rate of 0.015% per hour.
Standard Drink Definition
A standard drink is defined as 12 fluid ounces of beverage, with the alcohol content percentage determining the total amount of pure alcohol consumed. The calculator converts this into grams of alcohol using the density of pure alcohol (0.789 g/ml) for accurate BAC estimation.
The calculator provides your estimated BAC percentage and a corresponding status description. Understanding these results is crucial for making informed decisions about alcohol consumption and safety.
BAC Levels and Effects
- • 0.02% - Minimal mood changes
- • 0.04% - Feeling of relaxation
- • 0.08% - Legal intoxication limit in most countries
- • 0.15% - Significant impairment
- • 0.30% - Severe intoxication requiring medical attention
Important Considerations
This calculator provides estimates only and should not be used as a legal reference. Actual BAC can vary based on factors not included in the calculation, such as metabolism rate, food consumption, and overall health condition.
1. How accurate is the BAC calculator?
While the calculator uses scientifically validated formulas, it provides estimates only. Actual BAC can vary based on individual factors such as metabolism, food consumption, and overall health condition. For legal or medical purposes, always use professional testing methods.
2. Why does gender matter in BAC calculation?
Gender affects BAC because males and females typically have different proportions of body water content. Females generally have a higher percentage of body fat and less water content than males of the same weight, leading to higher BAC levels from the same amount of alcohol.
3. How long does it take for BAC to return to zero?
On average, the body eliminates alcohol at a rate of about 0.015% BAC per hour. However, this rate can vary based on individual factors. The only safe BAC level for driving is 0.00%.
4. Does food affect BAC levels?
Yes, food in your stomach can slow alcohol absorption, potentially leading to lower peak BAC levels. However, this calculator cannot account for food consumption, so actual BAC might be lower than calculated if you've eaten recently.
5. What is the scientific source for this calculator?
Blood alcohol estimates here rely on the Widmark formula, a method developed by Swedish physician Erik Widmark in the early 20th century that remains foundational in forensic and clinical toxicology. It accounts for body weight and a sex-specific distribution ratio reflecting average differences in body water content between men and women, then subtracts alcohol eliminated over time at a typical metabolic rate. Standard drink sizes and alcohol content figures used in the calculation follow guidance from the National Institute on Alcohol Abuse and Alcoholism, though individual metabolism can cause real BAC to differ from any formula-based estimate.