Your blood alcohol content decides whether you are legally fit to drive — and guessing it wrong has consequences. This calculator estimates your BAC with the Widmark formula, the same equation researchers have used for decades. It starts from the number of standard drinks (each holding 14 grams of pure alcohol, the US definition), spreads that alcohol through your body's water, then subtracts what your liver burns off at roughly 0.015 percent per hour.

Try a realistic night out: a 160-pound man has two beers over one hour. He types 2 into Standard Drinks, 1 into Hours Drinking, 160 into Body Weight, and picks the male option for Biological Sex. The result lands near 0.04 percent — under the 0.08 legal limit in every US state, but already past the point where judgment and reaction time start slipping. A 130-pound woman drinking the same amount would read higher, because the same alcohol dissolves into less body water.

This is an educational estimate, never a clearance to drive. Food, medications, fatigue, and individual metabolism shift real BAC in ways no formula captures. Police use calibrated breathalyzers; this calculator is not one. If you have been drinking, the only safe choice is not to drive.

With the pre-filled defaults — Standard Drinks (14g alcohol each) 2, Hours Drinking 2, Body Weight (lbs) 160, Biological Sex Male — the Blood Alcohol Content Calculator returns BAC Level (%) 0.499, Hours Until Sober 33.2. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.