It depends almost entirely on the quantity of alcohol had to drink. Every hour, the body burns through about one drink worth of alcohol (approximately 0.016 percent of BAC). Certain chemicals can even stay in your hair for up to 90 days. A typical urine test can pick up traces of alcohol for as long as 12 or even 48 hours after drinking. Some of the latest, most advanced tests can even measure alcohol levels for up to 80 hours after someone has had a drink.

Alcohol passes through your stomach and small intestines, where it gets absorbed through the bloodstream. The stomach absorbs about 20 percent of the alcohol, which goes straight to the blood vessels and, from there, to the brain. The small intestine absorbs the other 80 percent. Once it enters your bloodstream, your body metabolizes it at a rate of 20 milligrams per deciliter (mg/dL) per hour.