BAC Calculator
Estimate blood alcohol concentration with the Widmark formula from drinks, body weight, sex and time.
Runs 100% in your browser — nothing is uploaded.
Result
Formula
BAC = (alcohol g ÷ (r × weight g)) × 100 − 0.015 × hours
About this calculator
Estimates vary with food, medications and metabolism. There is no safe level for driving — never drive after drinking.
How to use
- 1
Enter your body weight in kilograms.
- 2
Select your sex and the number of standard drinks consumed.
- 3
Input the number of hours over which you were drinking, then view your estimated BAC and time to zero.
Frequently asked questions
How accurate is the BAC estimate?
It uses the Widmark formula with your weight, sex, number of standard drinks and drinking time — a good estimate, but food, medication and individual metabolism change the real value. There is no safe level for driving.
What is one standard drink?
About 14 g of pure alcohol — roughly 12 oz of beer (5%), 5 oz of wine (12%), or 1.5 oz of spirits (40%).
How long until my BAC reaches zero?
The body eliminates alcohol at roughly 0.015% per hour; the calculator estimates the time to zero using that rate.
Please note: Results are estimates for general information only and are not professional or medical/financial advice.