What does an online breathalyzer actually do?
An online BAC calculator estimates blood alcohol from the drinks, their strength, timing and your details. It does not sample your breath. A physical breathalyzer measures alcohol in exhaled air; use it according to its instructions.
When is an app useful?
If you want to keep count during the evening and explore an estimated alcohol curve, you can start with the calculator without buying a device. If you need a measurement, an app cannot replace the instrument. A predicted zero is not a measured zero.
How does the BAC calculator work?
The calculator converts each serving’s volume and strength into an amount of pure alcohol, then models absorption and elimination minute by minute. Weight, sex, age, height and food are included. It uses the Cheers model with standard hydration and one shared absorption rate for all servings online.
This is only an estimate. Never drive after alcohol.
Sources: NHTSA · Blood Alcohol Concentration
