Kentfield is a census-designated place in Marin County, California, United States, just north of San Francisco. Kentfield is located 2 miles southwest of downtown San Rafael, at an elevation of 115 feet. The population was 6,808 at the 2020 census. The ZIP codes are 94904 for street addresses, and 94914 for PO boxes, and are shared with the neighboring community of Greenbrae.