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Estimate your blood alcohol content from the drinks you have had, your body weight, sex and the time since your first drink, using the Widmark formula. This is a rough estimate only — read the safety note below and never use it to decide whether to drive.
What this BAC calculator does
This tool gives a quick estimate of your blood alcohol content (BAC) — the percentage of alcohol in your bloodstream — from four things you enter: how many standard drinks you have had, your body weight, your sex and how long ago you started drinking. It is a learning and planning aid, not a breathalyser. As the red note above says, the real figure varies with food, medication, metabolism and drink strength, so it must never be used to judge whether you are safe to drive.
How your BAC is worked out
The calculation uses the well-known Widmark formula. Each US standard drink is taken as 14 grams of pure alcohol, so the total alcohol is your number of drinks times 14. That is divided by your body weight in grams multiplied by a distribution factor — about 0.68 for men and 0.55 for women — and turned into a percentage. Finally it subtracts roughly 0.015% per hour since your first drink, because your liver steadily clears alcohol over time. The result is your estimated BAC right now.
Reading the result
The status box compares your estimate with the 0.08% legal driving limit used across the United States, and the time-until-sober figure shows roughly how long it would take to reach zero at the average clearance rate. Remember that many places set lower limits for commercial or young drivers, that impairment begins well below 0.08%, and that this is only an estimate. When you are planning food and drink more broadly, the TDEE Calculator and Water Intake Calculator cover the calorie and hydration side.