Stock Island, FL has a population of 4,214 and is the 7,202nd largest city in the United States. The population density is 5,037 per sq mi which is 1616% higher than the Florida average and 5460% higher than the national average. The median age in Stock Island is 43 which is approximately 3% higher than the Florida average of 42. In Stock Island, 42% of the population over 15 years of age are married, 50% speak English and 39% speak Spanish. 36% of Stock Island residents were born in Florida, 26% were born out of state, 2% were born outside of the United States and 37% were foreign born.