| | Sudley, VA | Fairfax, VA | United States |
| Population | 18,613 | 23,980 | 329,725,481 |
| Female Population | 47.7% | 51.2% | 50.5% |
| Male Population | 52.3% | 48.9% | 49.5% |
| Median Age | 34.5 | 37.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 15,283 | 22,616 | 309,327,143 |
| Population - 2000 | 7,719 | 21,498 | 285,036,114 |
| Population - 1990 | 7,321 | 19,622 | 251,960,433 |
| Pop. 2000 to Now | 143.7% | 9.0% | 15.6% |
| Pop. 1990 to Now | 156.9% | 19.4% | 30.8% |
| space4 | | | |
| Population Density | 6,753.6 | 3,843.0 | 93.4 |
| Land Area | 2.8 | 6.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Sudley, VA | Fairfax, VA | United States |
| Age 0 to 4 | 7.8% | 7.4% | 5.9% |
| Age 5 to 9 | 6.6% | 5.5% | 6.1% |
| Age 10 to 14 | 9.1% | 6.0% | 6.6% |
| Age 15 to 17 | 2.5% | 3.5% | 3.9% |
| Age 18 to 20 | 2.8% | 3.4% | 4.0% |
| Age 21 to 24 | 4.7% | 6.0% | 5.2% |
| Age 25 to 34 | 16.9% | 13.1% | 13.8% |
| Age 35 to 44 | 18.0% | 13.8% | 12.9% |
| Age 45 to 54 | 12.0% | 13.2% | 12.6% |
| Age 55 to 59 | 5.3% | 7.9% | 6.7% |
| Age 60 to 64 | 4.4% | 5.4% | 6.3% |
| Age 65 to 74 | 6.1% | 8.6% | 9.6% |
| Age 75 to 84 | 2.6% | 4.2% | 4.5% |
| Age 85 and over | 1.1% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Sudley, VA | Fairfax, VA | United States |
| White | 27.5% | 54.6% | 59.4% |
| Black | 9.7% | 5.4% | 12.2% |
| Asian | 10.2% | 18.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.3% | 0.4% |
| Two or More Races | 1.0% | 3.7% | 3.2% |
| Hispanic | 51.3% | 17.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Sudley, VA | Fairfax, VA | United States |
| Married Population | 49.7% | 56.3% | 49.8% |
| Currently Married | 45.6% | 55.1% | 48.0% |
| Married but Separated | 4.1% | 1.2% | 1.8% |
| Single Population | 50.3% | 43.7% | 50.2% |
| Never Married | 38.2% | 31.9% | 33.8% |
| Divorced | 8.6% | 7.3% | 10.8% |
| Widowed | 3.5% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 3.45 | 2.58 | 2.60 |
| Households | 5,387 | 9,090 | 124,010,992 |
| Family Households | 3,739 | 5,849 | 80,755,759 |
| Married couple, w/children | 43.9% | 41.2% | 30.5% |
| Married couple, no children | 25.8% | 42.7% | 42.9% |
| Non Family Households | 1,648 | 3,241 | 43,255,233 |
| Single householder, w/children | 18.8% | 6.1% | 15.8% |
| Single householder, no children | 11.5% | 10.0% | 10.8% |