Fallbrook, CA has a population of 31,771 and is the 1,340th largest city in the United States. The population density is 1,814 per sq mi which is 681% higher than the California average and 1903% higher than the national average. The median age in Fallbrook is 36 which is approximately 1% lower than the California average of 36. In Fallbrook, 62% of the population over 15 years of age are married, 62% speak English and 35% speak Spanish. 54% of Fallbrook residents were born in California, 24% were born out of state, 1% were born outside of the United States and 21% were foreign born.