Built and fact-checked by the DocNectar team — see our editorial standards
Key Features
Instant Calculation
Get accurate results in real time with our optimized algorithm.
Mobile Friendly
Fully responsive design. Works on all devices & screen sizes.
Privacy Focused
Your data stays on your device. We don't store any inputs.
100% Free
No hidden costs. This tool is completely free forever.
This calculator provides a rough, population-average estimate of blood alcohol content using the Widmark formula — it is not a substitute for a breathalyzer or blood test, and must never be used to decide whether it's safe to drive.
Real BAC varies significantly based on metabolism, food intake, medication, and other individual factors that this formula cannot account for. The only safe choice after drinking is not to drive.
How it works
Enter the number of standard drinks consumed, your body weight, your sex, and how many hours have passed since your first drink. The calculator applies the Widmark formula to estimate your blood alcohol content as a percentage.
- Enter standard drinks consumed.
- Enter body weight (lbs).
- Enter sex.
- Enter hours since first drink.
- Click Calculate to see your results.
Examples
Two drinks, one hour
A 160 lb male who had 2 standard drinks over the past hour has an estimated BAC of about 0.038% — this is only a rough estimate and should never inform a decision to drive.
Who should use it
- Learning how weight, sex, and time affect estimated blood alcohol levels.
- General alcohol education and awareness.
Industry applications
- Health and alcohol education
- Substance use awareness programs
Advantages
- Uses the standard, widely-referenced Widmark formula.
- Accounts for time elapsed and metabolism since the first drink.
Limitations
- Provides only a population-average estimate — real BAC varies by individual and cannot be measured without a breathalyzer or blood test.
Common mistakes to avoid
- Treating the estimate as precise enough to decide whether it's legal or safe to drive — it is not.
- Forgetting that food, medications, and individual metabolism all affect real BAC in ways this formula can't capture.
Best practices
- Use this tool only for general education about how alcohol, body weight, and time affect blood alcohol — never as a basis for deciding whether to drive.
Tips
- The only way to know your actual BAC is a breathalyzer or blood test — and the only guaranteed-safe choice after drinking is to not drive, regardless of what any estimate shows.