Blood Alcohol BAC Calculator
Estimate your blood alcohol content instantly using the Widmark formula. Understand how alcohol affects your body and know when it is safe to drive.
BAC Level
Current percentage
Sober Time
Hours until 0.00%
Safety Check
Driving legal status
Widmark
Standard formula
What is BAC?
Blood Alcohol Content (BAC) refers to the percentage of alcohol (ethanol) in a person's bloodstream. It is used to determine intoxication levels.
The Widmark Formula
This calculator uses the Widmark Formula, the most widely accepted method for estimating blood alcohol. It calculates the total weight of alcohol consumed and divides it by your body weight, adjusted for a gender-specific distribution constant, then subtracts the metabolic rate over time.
Body Weight Factor
A person who weighs less will have a higher BAC than a heavier person who drinks the same amount.
Gender Differences
Women typically have less body water and different enzyme levels, resulting in a higher BAC than men for the same intake.
Time Elapsed
The liver metabolizes alcohol at a rate of approximately 0.015% per hour. Time is the only way to get sober.
Custom Drinks
Add Beer, Wine, or Spirits individually to build an accurate timeline of your consumption.
Sober Countdown
Get an estimate of the exact time your body will return to a 0.00% blood alcohol level.
Legal Status
Compare your estimated result against common legal driving limits (e.g., 0.08%).
Why Choose Our Calculator?
100% Private
Your data never leaves your device. We do not store logs of your consumption or results, ensuring complete anonymity.
High Precision
We use the Widmark Formula with gender-specific constants (0.68 for men, 0.55 for women) for a more accurate scientific estimate.
Mobile Friendly
Designed for quick access on your phone, so you can check your status easily while you are out at an event.
Calculate Your BAC
Add your drinks below to see your status.
Add Drinks Consumed
How to Use the BAC Calculator
Get a reliable estimate in three easy steps.
Enter Personal Stats
Select your gender and enter your body weight. This determines how diluted the alcohol becomes in your body (distribution ratio).
Log Your Drinks
Use the quick buttons for Beer, Wine, or Shots. If you are drinking craft beer or cocktails, check the label and use the "Custom" fields to enter the exact Volume and ABV %.
Input Time Elapsed
Enter the hours passed since your first drink. This allows the calculator to subtract the alcohol your body has already metabolized.
BAC Levels & Effects
How different alcohol percentages affect your behavior and safety.
What is a Standard Drink?
In the US, a standard drink contains approx 14 grams of pure alcohol.
Regular Beer
12 fl oz
~5% Alcohol
Table Wine
5 fl oz
~12% Alcohol
Distilled Spirits
1.5 fl oz
~40% Alcohol
Applications of This Tool
Why knowing your numbers matters.
DUI Prevention
The primary use is estimating legal compliance. While not a legal defense, seeing a "0.09%" result can be the wake-up call needed to call a taxi instead of driving.
Pacing Yourself
Understanding how long it takes to metabolize alcohol helps in pacing drinks during social events. It helps clarify why "one drink an hour" might still lead to a high BAC for certain body weights.
Calculation Formula & Example
See exactly how the numbers are crunched using the Widmark Formula.
The Widmark Formula
Variables Defined:
- Alcohol Total mass of pure alcohol consumed in grams.
- Weight Body weight converted to grams.
- r Distribution ratio (0.68 for Men, 0.55 for Women).
- 0.015 Average metabolic elimination rate (percentage drop per hour).
Real World Example
Step 1: Calculate Alcohol Mass
3 beers × 12oz × 29.57 ml/oz = 1064ml total volume.
1064ml × 0.05 (ABV) × 0.789 (density) = 42g Alcohol.
Step 2: Calculate Body Distribution
Weight (g) × Ratio (Male)
81,650g × 0.68 = 55,522
Step 3: Determine Starting BAC
(42g / 55,522) × 100 = 0.075%
Step 4: Subtract Metabolism
0.075% - (2 hours × 0.015%)
0.075 - 0.030 = 0.045% Final BAC
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Frequently Asked Questions
Does eating food lower BAC?
Food slows the *absorption* of alcohol into the bloodstream, which can keep the peak BAC lower than on an empty stomach. However, it does not help your liver metabolize alcohol faster once it's in your blood.
Does coffee sober you up?
No. Coffee might make you feel more alert (masking the sedative effects), but it does not lower your Blood Alcohol Content. Time is the only thing that lowers BAC.
Is this calculator 100% accurate?
No calculator can be 100% accurate because individual metabolisms, medications, and genetics play a huge role. This tool provides a scientific estimate based on averages, not a medical guarantee.
What is the legal limit?
In the United States and UK, the legal limit for driving is typically 0.08%. However, impairment begins much earlier (around 0.04%), and commercial drivers often have lower limits (0.04%).