BAC Calculator
This tool is for educational purposes only. Never drink and drive.
About This Calculator
This BAC (blood alcohol concentration) calculator uses the Widmark formula to estimate the percentage of alcohol in your bloodstream based on the number and type of drinks consumed, your body weight, gender, and the time elapsed since your first drink. BAC depends on many individual factors including metabolism, food intake, medications, and tolerance, so this estimate should never be used to decide whether it is safe to drive. The legal BAC limit for driving is 0.08% in most US states, but impairment can begin at much lower levels. When in doubt, do not drive.
FAQ
What is blood alcohol concentration (BAC)?
BAC measures the amount of alcohol in your bloodstream as a percentage by weight. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. It is the standard measure used by law enforcement to determine legal intoxication.
How fast does the body metabolize alcohol?
On average, the body eliminates alcohol at a rate of about 0.015% BAC per hour, which is roughly equivalent to one standard drink per hour. This rate is relatively constant and cannot be sped up by drinking coffee, eating food, or taking a cold shower.
Why does gender affect BAC?
Women generally have a higher BAC than men after consuming the same amount of alcohol relative to body weight. This is because women typically have a lower proportion of body water (the Widmark r factor is 0.55 for women vs. 0.68 for men), which means alcohol is more concentrated in the bloodstream.
What is the legal BAC limit for driving?
In most US states, the legal limit is 0.08% BAC. However, many countries have lower limits (0.05% or even 0.00%). Commercial drivers in the US are held to a 0.04% limit. Impairment begins well before reaching the legal limit, so any amount of alcohol can affect driving ability.