Each alcoholic drink you have increases your BAC. However, most states only consider adult drivers alcohol-impaired when it reaches 0.08 g/dL (0.08%). The only exception is Utah — it implemented a BAC limit (0.05 g/dL) in December 2018.
The standard for commercial drivers is different. You are already alcohol-impaired if you operate a commercial motor vehicle (CMV) with a BAC of 0.04 g/dL.