Legally, you are considered to be driving under the influence if you have a minimum blood alcohol content (BAC) of:

Drivers age 21 and older are considered to be driving under the influence (DUI) if their BAC is 0.08 percent or greater. If a person's driving is impaired, they can be convicted of a DUI even if their BAC is lower than 0.08 percent. Drivers under age 21 can be convicted of illegal consumption of alcohol if their BAC is 0.02 percent or greater.