Blood Alcohol Content (BAC) Calculator

Estimate your current Blood Alcohol Content and impairment level.

Gender

Standard Drinks Consumed One standard drink equals 14g of pure alcohol.

Body Weight

Hours Since First Drink Time from start of drinking session.

Estimated Blood Alcohol Content

Estimated BAC (%)

Impairment Level

BAC Interpretation & Legal Limits

The legal limit for driving in most of the US and Canada is 0.08%.

Understanding the Widmark Formula and Your BAC

The **BAC Calculator** uses the modified Widmark formula to estimate your **Blood Alcohol Content** (**BAC**), the legal standard for intoxication. The formula accounts for the absorption of alcohol into the bloodstream and its metabolism over time, which are key variables in determining your **impairment level**.

The Widmark Formula Factors

The **Widmark formula** for calculating peak BAC is: $$\text{BAC} = \frac{\text{Alcohol in Grams} \times 100}{\text{Body Weight in Grams} \times r} - (\beta \times \text{Hours})$$ Where $r$ is the **Gender Factor** (distribution ratio) and $\beta$ is the rate of alcohol elimination (typically $0.015\%$).

**Alcohol in Grams:** Calculated from the number of **standard drinks** consumed.
**Body Weight:** A heavier person has more fluid volume to dilute the alcohol.
**Gender Factor ($r$):** Women typically have a higher ratio of fat to water, resulting in higher **BAC** for the same amount of alcohol. ($r \approx 0.68$ for men, $r \approx 0.55$ for women).
**Time Elapsed:** Alcohol is metabolized by the liver at a near-constant rate, subtracted from the total.

Legal and Impairment Limits

The typical **legal limit** for driving in many regions is **$0.08\%$ BAC**. However, impairment can begin much lower, affecting coordination and judgment. This **BAC estimate** should be treated as informational only, and if your result is close to the **legal limit**, you should absolutely avoid driving or operating machinery. Always prioritize safety when consuming alcohol.

BAC Calculator FAQs

What is the legal limit for driving (DUI/DWI)?

In most regions, the **legal limit** for operating a vehicle is a **Blood Alcohol Content (BAC)** of **$0.08\%$**. However, some jurisdictions enforce a lower limit for commercial drivers or zero tolerance for young drivers. You can feel impairment long before reaching the **legal limit**.

Why does gender affect the BAC calculation?

**Gender** affects **BAC** primarily because women typically have less water in their bodies than men of the same weight. Since alcohol distributes into body water, less water means the alcohol is less diluted, leading to a higher **BAC estimate** for women, even when consuming the same **standard drinks**.

How accurate is this estimated BAC?

The **BAC calculator** provides a scientific **estimate** based on averages. Actual **Blood Alcohol Content** can vary widely based on factors not used in the formula, such as food consumption, genetics, medication, and overall health. Never rely on this tool to determine if you are fit to drive. When in doubt, always arrange for sober transport.