Plain-language meaning
Blood alcohol concentration, or BAC, estimates how much alcohol is present in the bloodstream. It is often expressed as a percentage or as grams of alcohol per unit of blood, depending on the country and reporting system.
Example
A BAC calculator may estimate concentration from body weight, sex, drinks consumed and time. The result is only an approximation because absorption and elimination vary between people.
Legal and safety limits
BAC is legally and medically sensitive. Driving limits vary by country and sometimes by driver category. A calculator estimate must never be used to decide whether it is safe or legal to drive, operate equipment or make safety-critical decisions.
Limitations
Food, medication, health conditions, drink size, alcohol percentage, timing and individual metabolism can all change actual BAC. Only properly administered testing can measure BAC for legal or clinical purposes.
FAQ
Can a BAC calculator tell me if I can drive?
No. If alcohol is involved, the safer decision is not to drive. Use local law and official guidance, not a web estimate.
Why can two people have different BAC after the same drinks?
Body size, sex, time, food intake, drink strength and metabolism all affect the estimate.