| | Big Pine Key, FL | Cudjoe Key, FL | United States |
| Population | 4,752 | 2,315 | 329,725,481 |
| Female Population | 47.2% | 50.8% | 50.5% |
| Male Population | 52.8% | 49.2% | 49.5% |
| Median Age | 52.1 | 52.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,747 | 1,570 | 309,327,143 |
| Population - 2000 | 5,032 | 1,695 | 285,036,114 |
| Population - 1990 | 4,206 | 1,714 | 251,960,433 |
| Pop. 2000 to Now | 2.2% | 7.7% | 15.6% |
| Pop. 1990 to Now | 22.2% | 6.5% | 30.8% |
| space4 | | | |
| Population Density | 465.7 | 447.4 | 93.4 |
| Land Area | 10.2 | 5.2 | 3,531,905.4 |
| Water Area | 0.1 | 5.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Big Pine Key, FL | Cudjoe Key, FL | United States |
| Age 0 to 4 | 5.5% | 2.2% | 5.9% |
| Age 5 to 9 | 5.4% | 2.3% | 6.1% |
| Age 10 to 14 | 4.6% | 5.3% | 6.6% |
| Age 15 to 17 | 2.0% | 1.4% | 3.9% |
| Age 18 to 20 | 0.7% | 2.5% | 4.0% |
| Age 21 to 24 | 4.5% | 2.4% | 5.2% |
| Age 25 to 34 | 8.6% | 11.6% | 13.8% |
| Age 35 to 44 | 13.0% | 6.6% | 12.9% |
| Age 45 to 54 | 10.6% | 17.0% | 12.6% |
| Age 55 to 59 | 10.9% | 6.6% | 6.7% |
| Age 60 to 64 | 10.9% | 10.2% | 6.3% |
| Age 65 to 74 | 15.7% | 18.0% | 9.6% |
| Age 75 to 84 | 6.6% | 11.5% | 4.5% |
| Age 85 and over | 1.1% | 2.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Big Pine Key, FL | Cudjoe Key, FL | United States |
| White | 79.4% | 83.1% | 59.4% |
| Black | 0.5% | 0.0% | 12.2% |
| Asian | 0.8% | 0.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.5% | 8.1% | 3.2% |
| Hispanic | 17.8% | 8.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Big Pine Key, FL | Cudjoe Key, FL | United States |
| Married Population | 54.9% | 67.9% | 49.8% |
| Currently Married | 53.7% | 64.8% | 48.0% |
| Married but Separated | 1.2% | 3.1% | 1.8% |
| Single Population | 45.1% | 32.1% | 50.2% |
| Never Married | 22.7% | 10.0% | 33.8% |
| Divorced | 15.2% | 15.6% | 10.8% |
| Widowed | 7.2% | 6.5% | 5.6% |
| space5 | | | |
| Household Size | 2.50 | 2.32 | 2.60 |
| Households | 1,873 | 999 | 124,010,992 |
| Family Households | 1,193 | 636 | 80,755,759 |
| Married couple, w/children | 23.6% | 14.3% | 30.5% |
| Married couple, no children | 57.5% | 74.8% | 42.9% |
| Non Family Households | 680 | 363 | 43,255,233 |
| Single householder, w/children | 12.7% | 10.8% | 15.8% |
| Single householder, no children | 6.2% | 0.0% | 10.8% |