Rockville, MD is currently using an area code overlay in which area codes 240 and 301 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary.
In addition to Rockville, MD area code information read more about area codes 240 and 301 details and Maryland area codes.
Rockville, MD is located in Montgomery County and observes the Eastern Time Zone. View our Times by Area Code tool.