Area code 650 is a telephone area code in the North American Numbering Plan (NANP) for the San Francisco Bay Area in the U.S. state of California. It was split from area code 415 on August 2, 1997, and includes most of San Mateo County (except the northernmost portion), part of San Francisco, and the northwestern portion of Santa Clara County including Palo Alto, Mountain View, and Los Altos.

Prior to October 2021, area code 650 had telephone numbers assigned for the central office code 988. In 2020, 988 was designated nationwide as a dialing code for the National Suicide Prevention Lifeline, which created a conflict for exchanges that permit seven-digit dialing. This area code was therefore scheduled to transition to ten-digit dialing by October 24, 2021.