What does a BAC level mean?
BAC stands for blood alcohol concentration: the weight of alcohol in a given volume of blood. In U.S. notation, a BAC of 0.08% corresponds to 0.08 grams of alcohol per deciliter of blood (g/dL). Other reports may show the same concentration as mg/dL, g/L, or mg per 100 mL; use the BAC conversion calculator to translate the notation.
Illustrative BAC values are not personal predictions
The U.S. National Highway Traffic Safety Administration describes typical effects at several measured BAC values, including 0.02, 0.05, 0.08, 0.10, and 0.15 g/dL. People differ, the information is not a diagnosis, and a table cannot tell you how a particular person is functioning at a particular moment.
| Example measured value | What the notation means | Important limit |
|---|---|---|
| 0.02% BAC | 0.02 g/dL | Not a “safe” threshold |
| 0.05% BAC | 0.05 g/dL | Not a legal interpretation |
| 0.08% BAC | 0.08 g/dL | Not permission to drive |
| 0.15% BAC | 0.15 g/dL | Not a personal impairment diagnosis |
Why an online BAC calculator cannot measure a BAC level
A calculator must assume drink alcohol content, timing, body characteristics, absorption, and metabolism. Food, medication, health, pace of drinking, body composition, and the timing of individual drinks can change a real result. A breath or blood test is needed to measure BAC. Our methodology explains the assumptions behind this site's educational model.
Use the right BAC tool
- BAC Calculator — estimate a range from individual drinks and context.
- BAC Calculator Over Time — illustrate how the same model changes across future hours.
- BAC Conversion Calculator — translate a percentage into equivalent concentration units.
- What is BAC? — read the plain-language definition and measurement basics.