Blood Alcohol Content Estimator
How it works
This runs the Widmark formula: standard drinks convert to grams of pure alcohol (14g each), which spread through a fraction of body weight called the distribution ratio — 0.68 for men, 0.55 for women, standard Widmark constants reflecting average body water content. Elapsed time then burns off alcohol at a flat average rate of 0.015% per hour. The result is floored at zero, since a person cannot become "more sober than sober" just because more time passed.
Every input feeding that formula is an average, not a measurement of the specific body typing them in — see the FAQ below for what it leaves out.
This is a rough population-average estimate, not a measurement of you. It should never be used to decide whether it's safe to drive — if you've been drinking, the safe choice is simply not to drive, regardless of what any number here says.
Frequently asked questions
Why can this only ever be a rough estimate?
The Widmark formula it runs on is a population average: it knows your drink count, weight, sex and elapsed time, and nothing else. Food in your stomach, how fast you drank, medication, liver function and plenty of other things all change how alcohol actually behaves in a real body, sometimes by a lot. Two people with identical inputs here can have quite different real BAC.
What exactly counts as a "standard drink"?
In the US, 14 grams of pure alcohol — roughly one 12 fl oz beer at 5% ABV, one 5 fl oz glass of wine at 12%, or one 1.5 fl oz shot of spirits at 40%. Bigger pours or stronger drinks count as more than one. If you only know a beverage's volume and ABV, the Standard Drink Calculator converts that into a drink count first.
Can I use this to decide if I'm okay to drive?
No — never. This estimate cannot know your actual impairment, and legal limits, tolerance and judgement are all separate from a number a webpage guesses at. If you've had anything to drink, don't drive. Plan a ride, a taxi, or a sober driver before you start drinking, not after.