BAC Calculator
Produce a deliberately cautious, very rough blood alcohol estimate.
Do not use this estimate to decide whether to drive or perform a safety-critical task. Alcohol absorption and elimination vary substantially.
How to use this calculator
- Enter equation sex, weight, number and size of drinks, ABV, and elapsed time.
- Review the live result and use Copy result when you need to share it.
How the calculation works
A Widmark-style estimate divides alcohol grams by body water distribution and subtracts a fixed hourly elimination assumption.
Formula
A Widmark-style estimate divides alcohol grams by body water distribution and subtracts a fixed hourly elimination assumption.
Step-by-step calculation
- Enter equation sex, weight, number and size of drinks, ABV, and elapsed time.
- A Widmark-style estimate divides alcohol grams by body water distribution and subtracts a fixed hourly elimination assumption.
- Check the displayed result, then copy it if needed.
Worked example
Two 150 mL glasses at 12% over two hours produce only a rough model estimate; it cannot establish fitness to drive.
Risk guidance
Frequently asked questions
Does this tool send my inputs anywhere?
No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.
How should I use the result?
Check that the entered units and values match your situation, especially around dates, breaks, and rounding.
Related tools
Body Surface Area Calculator
Estimate body surface area with the Mosteller formula.
Open tool