Fairfield, CA has a population of 110,953 and is the 260th largest city in the United States. The population density is 2,705 per sq mi which is 1064% higher than the California average and 2886% higher than the national average. The median age in Fairfield is 34 which is approximately 4% lower than the California average of 36. In Fairfield, 55% of the population over 15 years of age are married, 64% speak English and 21% speak Spanish. 53% of Fairfield residents were born in California, 22% were born out of state, 3% were born outside of the United States and 22% were foreign born.