San Mateo, CA is currently using one area code which is area code 650. Area code 650 was created from a split of area code 415 and put into service on August 2, 1997.
In addition to San Mateo, CA area code 650 serves most of San Mateo County and a small area in northwest Santa Clara County, including the larger cities and communities of Belmont, Burlingame, Daly City, East Palo Alto, Foster City, Los Altos, Menlo Park, Millbrae, Mountain View, Pacifica, Palo Alto, Redwood City, San Bruno, San Carlos, San Mateo, and South San Francisco area, in addition to many smaller communities within the area code 650 service area.
San Mateo, CA is located in San Mateo County and observes the Pacific Time Zone. View our Times by Area Code tool.