Blood Alcohol Concentration (BAC) Calculator

Gender: Body Weight (kg): Time Since First Drink:

Alcohol Consumed

Beer (5% ABV, 12oz/330ml): Wine (12% ABV, 5oz/150ml): Liquor (40% ABV, 1.5oz/50ml): Other Alcohol (ml, specify volume & ABV):

Blood Alcohol Concentration (BAC) Calculator Online – Estimate BAC Easily

Intro

A Blood Alcohol Concentration (BAC) Calculator is a free online tool that helps you estimate the amount of alcohol in your bloodstream based on your weight, gender, drinks consumed, and time passed since drinking. BAC is expressed as a percentage and is widely used to determine levels of intoxication, fitness to drive, or potential health risks.

Manually calculating BAC can be complex since it involves multiple factors and formulas. The BAC Calculator online simplifies this process, giving you quick and accurate results in seconds. Whether you’re a student learning about alcohol metabolism, an individual curious about safe drinking limits, or someone monitoring responsible alcohol use, this tool is easy, fast, and reliable.

Formula / Working

The calculator generally applies the Widmark Formula, one of the most recognized methods for estimating BAC: BAC=(Alcohol Consumed in grams)(Body Weight in grams×r)×100BAC = \frac{(Alcohol\ Consumed\ in\ grams)}{(Body\ Weight\ in\ grams \times r)} \times 100BAC=(Body Weight in grams×r)(Alcohol Consumed in grams)×100

Where:

r = alcohol distribution ratio (0.68 for men, 0.55 for women)
Alcohol Consumed = number of drinks × alcohol by volume (ABV) × drink size × 0.789 (ethanol density factor)
Time factor = BAC decreases approximately 0.015% per hour as the body metabolizes alcohol.

The calculator uses these inputs—weight, gender, number of drinks, ABV, and drinking time—to instantly compute your estimated BAC.

Step-by-Step Usage

Here’s how to use the BAC Calculator online:

Open the Blood Alcohol Concentration Calculator in your browser.
Select your gender (male/female).
Enter your weight (in kg or lbs).
Input the number of drinks consumed and their alcohol content (ABV %).
Add the time passed since your first drink.
Click the Calculate button.
Instantly view your estimated BAC result along with an interpretation (e.g., safe, impaired, or illegal for driving).

Examples

Example 1:

Male, Weight = 80 kg
Drinks = 3 beers (355 ml each, 5% ABV)
Time elapsed = 2 hours

Calculation:

Total alcohol ≈ 42 g
BAC ≈ 0.06% after metabolism adjustment

Interpretation: Slightly above the typical legal driving limit in many countries (0.05%).

Example 2:

Female, Weight = 60 kg
Drinks = 2 glasses of wine (150 ml each, 12% ABV)
Time elapsed = 1.5 hours

Calculation:

Total alcohol ≈ 28 g
BAC ≈ 0.07% after metabolism adjustment

Interpretation: Likely impaired and above legal driving limit (0.05%).

Example 3:

Male, Weight = 90 kg
Drinks = 1 shot of whiskey (45 ml, 40% ABV)
Time elapsed = 1 hour

Calculation:

Total alcohol ≈ 14 g
BAC ≈ 0.02%

Interpretation: Low BAC; effects are mild but caution still advised.

FAQs

Q1. What is Blood Alcohol Concentration (BAC)?
BAC is the percentage of alcohol present in your blood. For example, a BAC of 0.08% means 0.08 grams of alcohol per 100 ml of blood.

Q2. What is the legal BAC limit for driving?
In many countries, the legal limit is 0.05% or 0.08%, but this varies. Always check local laws.

Q3. Is this calculator 100% accurate?
No, it provides an estimate based on standard formulas. Factors like metabolism, health, and food intake can affect real BAC levels.

Q4. How fast does the body metabolize alcohol?
On average, the body reduces BAC by about 0.015% per hour, but this may vary.

Q5. Who can use the BAC Calculator?
Anyone interested in estimating alcohol effects, but it should never be a substitute for professional medical advice or legal testing methods like a breathalyzer.