Fountain Valley, CA has a population of 56,670 and is the 703rd largest city in the United States. The population density is 6,246 per sq mi which is 2588% higher than the California average and 6795% higher than the national average. The median age in Fountain Valley is 44 which is approximately 22% higher than the California average of 36. In Fountain Valley, 59% of the population over 15 years of age are married, 59% speak English and 9% speak Spanish. 49% of Fountain Valley residents were born in California, 19% were born out of state, 1% were born outside of the United States and 31% were foreign born.