How to use the BAC Calculator
The BAC calculator gives a rough estimate of blood alcohol concentration using the Widmark formula.
What you need to enter
- Sex
- Weight (kg)
- Standard drinks (14 g alcohol)
- Hours since first drink
The formula
BAC ≈ alcohol grams ÷ (body weight × distribution ratio) × 100 − 0.015 per hour.
Worked example
Using the default values in the calculator:
- Sex: Male
- Weight (kg): 75
- Standard drinks (14 g alcohol): 3
- Hours since first drink: 2
| Estimated BAC | 0.052 % |
| Time until sober | 3.5 hours |
Tips for better results
- Never drive after drinking.
- Food, medication and fitness change real BAC.
Common mistakes to avoid
- Using it to decide if you are safe to drive.
- Assuming equal results for everyone.
Please note: Health calculators and guides give general estimates, not medical advice. Talk to a doctor or other qualified professional about your own health. See our Disclaimer.