Big Pine Key, FL has a population of 4,902 and is the 6,559th largest city in the United States. The population density is 480 per sq mi which is 64% higher than the Florida average and 430% higher than the national average. The median age in Big Pine Key is 55 which is approximately 31% higher than the Florida average of 42. In Big Pine Key, 59% of the population over 15 years of age are married, 86% speak English and 10% speak Spanish. 22% of Big Pine Key residents were born in Florida, 64% were born out of state, 1% were born outside of the United States and 13% were foreign born.