Neptune Beach, FL has a population of 6,817 and is the 5,274th largest city in the United States. The population density is 2,924 per sq mi which is 896% higher than the Florida average and 3127% higher than the national average. The median age in Neptune Beach is 42 which is approximately 1% higher than the Florida average of 42. In Neptune Beach, 55% of the population over 15 years of age are married, 97% speak English and 1% speak Spanish. 45% of Neptune Beach residents were born in Florida, 50% were born out of state, 2% were born outside of the United States and 4% were foreign born.