Total Alcohol Consumed
Multiply each drink's volume by its ABV to get grams of alcohol. totalAlcohol = Σ (volume × abv × 0.789), where 0.789 converts milliliters of ethanol to grams.
Health
About Blood Alcohol Calculator
Estimate BAC by weight and drink total, then see how the estimate fades over time.
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About this calculator
What this does
Estimates blood alcohol content (BAC) based on your body weight, the number and type of drinks consumed, the alcohol percentage of each drink, and the time elapsed since you started drinking. It also shows how your estimated BAC declines over time as your body metabolizes alcohol.
Who it is for
Anyone looking for a general reference on how alcohol consumption affects BAC levels. Commonly used as an educational tool to understand the relationship between drinking and estimated BAC, not for legal or medical decisions.
How it works
The calculator uses a Widmark-style formula that divides total alcohol consumed by your estimated body water volume (based on weight and sex), then subtracts an average metabolic elimination rate multiplied by elapsed hours. The result is a rough BAC estimate that trends downward over time.
Limitations
This is an estimate only. Actual BAC varies significantly based on metabolism, food intake, medications, hydration, health conditions, and many individual factors. It should never be used to determine fitness to drive or for any legal or medical purpose.
Formula
Widmark BAC Estimate
Divide total alcohol by body water volume estimated from weight and sex. bac = totalAlcohol / (weight × distributionRatio × 10), then subtract metabolism.
BAC Over Time
Subtract the metabolized amount based on hours elapsed since drinking started. currentBAC = initialBAC − (eliminationRate × hoursElapsed). The typical elimination rate is 0.015 BAC per hour.
How it works
Step 1
Enter your body weight
Input your weight in pounds or kilograms using the unit toggle. The calculator uses this to estimate your body water volume.
Step 2
Select your sex
Choose male or female. The Widmark formula uses different distribution ratios for each sex, which affects the BAC estimate.
Step 3
Add drinks
Enter the number of drinks, the volume per drink, and the alcohol by volume (ABV) percentage. You can add multiple drink types to reflect what you actually consumed.
Step 4
Set the elapsed time
Enter how many hours have passed since you started drinking. The calculator subtracts the metabolized alcohol to estimate your current BAC.
Step 5
Review the estimate
The calculator shows your estimated BAC and a graph of how it declines over the next several hours as your body metabolizes the alcohol.
Step 6
Understand the limitations
This is a rough educational estimate. Never use it to decide if you are safe to drive or for any legal or medical purpose.
Reference ranges
Mild Impairment
0.02–0.05% BAC. Some loss of judgment and relaxation. Below the legal limit in all US states.
Legal Limit Boundary
0.05–0.08% BAC. Increased impairment. 0.08% is the standard legal driving limit in most US states.
Significant Impairment
0.08–0.15% BAC. Poor coordination, slowed reaction time, and reduced judgment. Legal consequences for driving.
Severe Intoxication
0.15% and above. High risk of blackout, vomiting, and alcohol poisoning. Emergency medical attention may be needed.