Alcohol Metabolism Calculator
A rough sense of how long it takes to clear. Rough is the operative word.
Reading your result
Fill in every field and the steps will be spelled out here.
How it is calculated
This is an estimate, not a measurement. The Widmark formula uses only weight and sex, so it knows nothing about liver function, body composition, whether you ate, medication, or genetic variation in alcohol dehydrogenase. The same person drinking the same amount can land in a different place on a different night.
Women clear the same volume more slowly. A lower proportion of body water means the same alcohol is distributed in a smaller volume, producing a higher concentration at identical body weight.
Elimination runs at a near-fixed rate — roughly 0.015% per hour — and nothing speeds it up. Coffee, a shower, exercise and food do not change it. Feeling sober and being under a limit are different states, and the first arrives well before the second.
This calculator does not tell you when it is safe to drive. The error band is wide enough to straddle legal limits, which makes it dangerous for that purpose. If you have been drinking, not driving — including the following morning — is the only answer this tool can stand behind.
Frequently asked questions
Will a night of sleep clear it?
Not necessarily. Elimination continues at the same rate while you sleep, so a late heavy night can still leave a meaningful concentration by morning. This is where morning-after driving offences come from.
Does food or coffee speed it up?
No. The rate is set by the liver and is close to constant. Food slows absorption and water helps with dehydration, but neither changes how fast alcohol leaves the blood.
How far off can the estimate be?
Substantially — individual variation is large, and whether you drank on an empty stomach or over several hours changes the absorption curve. Treat the output as a range, not a number.
A Widmark estimate that can differ substantially from measured blood alcohol concentration. Do not use it to decide whether to drive. After drinking, the safe course is not to drive regardless of elapsed time.