About this Calculator
Blood Alcohol Concentration (BAC) measures the percentage of alcohol in a person’s bloodstream. Use this tool to estimate your impairment levels.
Formula & Calculations
Mathematical Formula
Widmark Formula (incorporating body water indices)
Calculates alcohol grams divided by body water, adjusted for elapsed hours.
How to Calculate Step-by-Step
1
Count drinks
Total standard units consumed.
2
Factor weight
Calculate ratio relative to body mass water index.
How to Use & Best Practices
Enter gender, weight, drinks consumed, and hours elapsed.
Frequently Asked Questions
What is the legal driving limit?
Typically 0.08% BAC in the US, and 0.05% in many parts of Europe.