BAC Calculator
0.000 estimated BAC
Safety warning: This is a rough mathematical estimate only, not a measurement of your actual blood alcohol content. Food intake, medications, liver function, hydration, genetics, and many other factors this calculator cannot account for all change your real BAC. Never use this number to decide whether it is safe to drive. If you have been drinking at all, use a designated driver, rideshare, or taxi — every time, regardless of what this or any estimate shows.
How This Estimate Is Calculated
This calculator uses the Widmark formula, the standard equation used since the 1930s to estimate blood alcohol concentration from alcohol dose, body weight, and time elapsed: BAC = (Alcohol consumed in grams / (Body weight in grams × Widmark factor r)) × 100, minus the amount metabolized over time (elimination rate of about 0.015% per hour). The Widmark factor r represents the fraction of body weight that alcohol distributes into — this calculator uses the commonly cited averages of 0.68 for men and 0.55 for women, reflecting typical differences in body water composition. Each "standard drink" is treated as 14 grams of pure alcohol, the U.S. definition.
Why Your Real BAC Can Differ Significantly
The Widmark formula was designed as a population-average estimate, not a precise measurement of any one individual. Real BAC is affected by how much food is in your stomach, how fast you drank, medications, liver health, muscle-to-fat ratio, and normal biological variation — actual test results can differ substantially from this estimate in either direction. Only a breathalyzer or blood test administered by a professional gives an actual, legally meaningful reading.
The Only Safe Rule After Drinking
No calculator, app, or personal "trick" can reliably tell you it's safe to drive after drinking. Impairment starts well below the legal limit, and reaction time, judgment, and coordination can be affected even when you feel fine. If you plan to drink, arrange a designated driver, rideshare, or taxi before you start. This tool is for general education about how alcohol is metabolized, not medical advice or a safety determination — for concerns about drinking habits or alcohol dependence, talk to a doctor or qualified health professional. You may also find the calorie calculator useful for understanding the calories that alcoholic drinks add to your day.
Frequently Asked Questions
How accurate is this BAC calculator?
It provides a rough population-average estimate using the Widmark formula, not a precise measurement. Food intake, medications, hydration, liver function, and individual metabolism can all shift your real BAC well above or below the estimate, so it should never be treated as an exact number.
Can I use this calculator to decide if I'm okay to drive?
No. This estimate must never be used to decide whether it is safe to drive. Impairment can occur below the legal limit and varies by person, so the only safe choice after drinking is a designated driver, rideshare, or taxi, regardless of the number this calculator shows.