In almost every state, a DUI conviction—even a first offense—is considered a misdemeanor crime. But, in some circumstances, a DUI can be a felony.
Generally, it's possible to be convicted of a DUI as a misdemeanor or a felony. A standard first offense is almost always going to be a misdemeanor. But a DUI offender who kills or seriously injures another person is typically looking at felony charges—even if it's the person's first offense. (A driver could also face vehicular homicide charges for a DUI-related killing.)
Having prior DUI convictions can also elevate a DUI to a felony. In some states, first and second DUI offenses are misdemeanors but a third or subsequent conviction is a felony.
There are also states that make a DUI a felony if the driver had a particularly high blood alcohol concentration (BAC) or was transporting children while driving under the influence.
The main difference between a misdemeanor and felony DUI is the resulting penalties of a conviction. For misdemeanor DUIs, the convicted motorist is typically looking at a maximum of one year in jail and up to $1,000 in fines (take or give). But felony DUIs can result in a year or more in jail or prison and thousands of dollars in fines. And, typically, the license suspension period for a DUI conviction that's a felony is going to be longer than for a misdemeanor conviction. A felony conviction can also come with additional consequences such as the loss of voting rights.