Fillmore, CA has a population of 15,391 and is the 2,770th largest city in the United States. The population density is 4,576 per sq mi which is 1869% higher than the California average and 4950% higher than the national average. The median age in Fillmore is 34 which is approximately 6% lower than the California average of 36. In Fillmore, 56% of the population over 15 years of age are married, 38% speak English and 61% speak Spanish. 62% of Fillmore residents were born in California, 9% were born out of state, 1% were born outside of the United States and 28% were foreign born.