| | Montauk, NY | Fire Island, NY | United States |
| Population | 4,272 | 347 | 329,725,481 |
| Female Population | 43.9% | 46.7% | 50.5% |
| Male Population | 56.1% | 53.3% | 49.5% |
| Median Age | 51.8 | 48.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,157 | 264 | 309,327,143 |
| Population - 2000 | 3,851 | 310 | 285,036,114 |
| Population - 1990 | 3,001 | 270 | 251,960,433 |
| Pop. 2000 to Now | -6.1% | -21.6% | 15.6% |
| Pop. 1990 to Now | 20.6% | -10.0% | 30.8% |
| space4 | | | |
| Population Density | 244.4 | 37.7 | 93.4 |
| Land Area | 17.5 | 9.2 | 3,531,905.4 |
| Water Area | 2.3 | 29.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Montauk, NY | Fire Island, NY | United States |
| Age 0 to 4 | 6.1% | 4.6% | 5.9% |
| Age 5 to 9 | 5.5% | 4.9% | 6.1% |
| Age 10 to 14 | 4.8% | 9.5% | 6.6% |
| Age 15 to 17 | 2.4% | 2.0% | 3.9% |
| Age 18 to 20 | 1.2% | 6.1% | 4.0% |
| Age 21 to 24 | 3.3% | 2.9% | 5.2% |
| Age 25 to 34 | 11.8% | 5.2% | 13.8% |
| Age 35 to 44 | 10.4% | 11.8% | 12.9% |
| Age 45 to 54 | 12.5% | 19.3% | 12.6% |
| Age 55 to 59 | 6.2% | 7.5% | 6.7% |
| Age 60 to 64 | 10.8% | 10.7% | 6.3% |
| Age 65 to 74 | 16.0% | 8.6% | 9.6% |
| Age 75 to 84 | 6.2% | 4.3% | 4.5% |
| Age 85 and over | 2.9% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Montauk, NY | Fire Island, NY | United States |
| White | 91.8% | 57.3% | 59.4% |
| Black | 1.1% | 18.2% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.4% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.6% | 0.0% | 0.4% |
| Two or More Races | 1.8% | 0.0% | 3.2% |
| Hispanic | 4.3% | 24.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Montauk, NY | Fire Island, NY | United States |
| Married Population | 59.9% | 59.4% | 49.8% |
| Currently Married | 58.6% | 58.4% | 48.0% |
| Married but Separated | 1.3% | 1.1% | 1.8% |
| Single Population | 40.1% | 40.6% | 50.2% |
| Never Married | 30.4% | 26.7% | 33.8% |
| Divorced | 6.9% | 11.0% | 10.8% |
| Widowed | 2.7% | 2.8% | 5.6% |
| space5 | | | |
| Household Size | 2.65 | 3.56 | 2.60 |
| Households | 1,571 | 95 | 124,010,992 |
| Family Households | 1,112 | 75 | 80,755,759 |
| Married couple, w/children | 25.8% | 33.3% | 30.5% |
| Married couple, no children | 59.7% | 46.7% | 42.9% |
| Non Family Households | 459 | 20 | 43,255,233 |
| Single householder, w/children | 8.7% | 13.3% | 15.8% |
| Single householder, no children | 5.8% | 6.7% | 10.8% |