BAC Calculator

It uses the Widmark formula, a method developed in 1932 that's still the basis of most consumer BAC estimators today. It takes the total grams of alcohol you drank, divides that by your body weight and a distribution ratio (0.68 for men, 0.55 for women, reflecting average body water content), and then subtracts an estimate of how much your liver has already metabolized based on the time elapsed. It's a useful educational estimate, not a measurement of your actual blood alcohol level.

No. This is a population-average estimate from a formula that can't account for your food intake, medication, liver health, fatigue, or how fast you actually drank. Driving skills measurably decline well below 0.05% BAC, so a number that shows you're under a legal limit does not mean you're unaffected. If you've been drinking, the safest choice is not to drive — use a taxi, rideshare, or a sober driver instead.

It depends on where you are, and limits can even vary within a country. In most of the US it's 0.08% (0.05% in Utah), in England, Wales and Northern Ireland it's 0.08% (0.05% in Scotland), in India it's 0.03%, and the UAE has zero tolerance for any detectable alcohol. Many places also apply stricter limits to commercial or newly licensed drivers, so check your local rules rather than relying on a general figure.

The formula uses a distribution ratio that reflects average body water content, which tends to be lower in women than in men. Because alcohol dissolves into body water rather than fat, a lower ratio concentrates the same amount of alcohol into a smaller volume, so women typically end up with a higher estimated BAC than men of similar weight after drinking the same amount.

On average, the liver clears alcohol at roughly 0.015% BAC per hour, though this varies from person to person based on genetics, liver health, and other factors. Nothing you can do — coffee, cold showers, exercise, or sleep — speeds this up; only time actually lowers your BAC. If you want to know how long until you reach 0.00%, this calculator gives a rough estimate based on that average rate.