Blood Alcohol Calculator (BAC estimate)
Estimate your blood alcohol level (g/L) using the Widmark formula.
Result
Estimated BAC (g/L)
0.42
How it works
This estimates blood alcohol concentration from the alcohol consumed, body weight and time elapsed, using a Widmark-style calculation. The subtraction of roughly 0.15 per hour reflects how steadily the liver clears alcohol. That elimination rate is the crucial fact: it is fixed. The liver processes roughly one standard drink per hour and cannot be hurried, which is why time is the only thing that lowers the number. Coffee, a cold shower or food after drinking change how awake you feel, not how much alcohol is in your blood. The estimate is genuinely rough. Sex, body composition, metabolism, medication, whether you ate before drinking and even the day itself all shift the real value substantially. **Never use this to decide whether to drive.** The only safe amount before driving is none, and legal limits differ by country and by licence type.
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Frequently asked questions
How much is one standard drink?
About 10 g of pure alcohol (a small beer, a glass of wine or a shot).
Can I rely on this to drive?
No. It is an estimate only; the only safe level for driving is zero. Never drive after drinking.
Does coffee or a shower lower blood alcohol?
No. Neither does exercise, water or eating after the fact. They may make you feel more alert, which is dangerous precisely because it disguises impairment. Only the passage of time reduces blood alcohol.
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