San Jose, California has a smaller population than San Diego.
San Diego . With an estimated population of 1,394,928 as of July 1 , 2015 , San Diego is the eighth-largest city in the United States and second-largest in California . San Jose, California . With an estimated 2015 population of 1,026,908 , it is the third most populous city in California ( after Los Angeles and San Diego ) and the tenth most populous in United States . Results of the 1990 U.S. Census indicated that San Jose had officially surpassed San Francisco as the most populous city in Northern California .